A Check Engine Light can appear without any dramatic change in the way your Toyota drives, leaving many owners wondering whether the problem is serious or simply related to emissions. Toyota P0418 is one of those diagnostic trouble codes that can be easy to overlook because the engine may continue to start and run normally. However, the code points to a fault within the electrical control circuit associated with the Secondary Air Injection System, an emissions system that operates under specific engine conditions, particularly during cold starts.
Understanding Toyota P0418 requires more than identifying a failed component. The secondary air injection system depends on several interconnected components, including the air injection pump, switching valves, relays, fuses, wiring, connectors, power supply, ground circuits, and the engine control module. A problem in any relevant part of this circuit can affect how the system responds to the ECM command and may trigger P0418.
The exact diagnostic definition and component configuration can vary according to the Toyota model, model year, engine, market, and emissions system design. For that reason, P0418 should be treated as a starting point for diagnosis rather than an automatic instruction to replace a pump or valve. In this guide, you will learn what Toyota P0418 means, the symptoms and causes to look for, how technicians diagnose the circuit, what repairs may be required, how much they can cost, and when it is safe to continue driving.
What Does the Toyota P0418 Code Mean?
Toyota P0418 is an OBD-II diagnostic trouble code associated with a fault in the electrical control circuit of the Secondary Air Injection System. The secondary air injection system is part of the vehicle’s emissions control strategy and is designed to introduce additional air into the exhaust stream under specific operating conditions. By supplying oxygen to the exhaust during cold-start operation, the system helps promote more complete combustion of residual hydrocarbons and allows the catalytic converter to reach its effective operating temperature more quickly.
The P0418 code is generally associated with the switching or control circuit identified as “B” within this system. The ECM monitors the electrical response of the relevant circuit and compares the expected operation with the signals or conditions it receives. When the circuit does not behave as expected, the ECM can store P0418 and illuminate the Check Engine Light. This means the code describes a detected electrical or control-system problem, but it does not automatically identify which physical component has failed.
The exact factory definition of Toyota P0418 can vary depending on the Toyota model, model year, engine, emissions configuration, and market. The system may include a secondary air injection pump, air switching valves, relays, fuses, wiring harnesses, connectors, power and ground circuits, and ECM control. Consequently, a proper diagnosis should begin by confirming the vehicle-specific definition and factory wiring diagram before testing individual components.
This distinction is important because replacing the secondary air injection pump simply because P0418 is present can result in unnecessary expense. A damaged wire, corroded connector, failed relay, poor ground, voltage problem, or control-circuit fault may produce the same diagnostic code. Understanding how these components interact provides the foundation for accurately diagnosing and repairing Toyota P0418.
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Common Symptoms of Toyota P0418
When Toyota P0418 is stored, the symptoms can range from a simple Check Engine Light to noticeable changes in engine behavior, depending on the vehicle and the underlying electrical fault. Because the Secondary Air Injection System usually operates under specific conditions rather than continuously, a failure may not immediately affect everyday driving. In many cases, the driver can start and operate the Toyota normally while the ECM continues to detect that the secondary air injection circuit is not responding as expected.
The most obvious symptom is often the Check Engine Light. The warning may appear after the ECM completes its monitoring sequence and determines that the relevant secondary air injection control circuit has an electrical problem. Depending on the Toyota’s diagnostic strategy, the code may initially remain pending before becoming confirmed after the fault is detected during additional drive cycles. Other emissions-related diagnostic codes can also appear at the same time, particularly when the underlying problem affects more than one component or circuit.
Some Toyota vehicles may exhibit unusual behavior during cold starts. The secondary air injection pump or associated switching components may produce an abnormal operating sound, fail to operate when commanded, or operate inconsistently. If the electrical problem is accompanied by another fault within the emissions system, the engine may experience rough operation immediately after startup, although this is not a universal symptom of P0418. A vehicle with an isolated control-circuit fault can continue to run smoothly because the secondary air injection system is not responsible for normal fuel delivery or basic ignition control.
Intermittent symptoms are also possible. A damaged wire, loose terminal, corroded connector, weak ground, or unstable power supply can cause the fault to appear only under certain temperature, vibration, moisture, or load conditions. This can make Toyota P0418 particularly difficult to diagnose when the vehicle behaves normally during a workshop inspection. For that reason, the warning light, stored and pending codes, freeze-frame information, and live electrical data should be considered together rather than relying only on what the driver can feel.
Common Causes of Toyota P0418
The causes of Toyota P0418 are closely connected to the electrical and control architecture of the Secondary Air Injection System. Although the code may lead some owners to suspect a failed secondary air injection pump immediately, the actual fault can originate anywhere along the circuit that supplies power, controls the switching component, or communicates the expected electrical response back to the ECM. This is why the presence of P0418 should not be treated as proof that one specific component has failed.
Wiring problems are among the important areas to inspect. An open circuit, short circuit, damaged insulation, high resistance, or an intermittent connection can prevent the ECM from controlling the secondary air injection system correctly. Wiring located near the engine compartment can be exposed to heat, vibration, moisture, and contamination, which can gradually weaken the insulation or terminals. A circuit may appear visually intact while still developing excessive resistance under load, making voltage-drop testing more useful than a simple continuity check in some cases.
Electrical connectors and terminals can create similar problems. Corrosion, water intrusion, loose terminals, poor pin contact, or damaged connector locks can interrupt the control signal or power supply. Fuse and relay faults should also be considered because the secondary air injection pump and switching components depend on correctly functioning electrical protection and switching circuits. A weak relay, blown fuse, or poor connection can prevent the commanded component from operating even when the component itself is mechanically sound.
Power supply and ground conditions are another important part of the diagnostic path. Low system voltage, a poor engine or chassis ground, battery problems, or charging-system abnormalities can interfere with the operation of electronically controlled emissions components. Depending on the Toyota application, a fault involving the switching valve, secondary air injection pump, or another control component may also trigger P0418. In less common cases, the ECM or its control circuit may be involved, but this possibility should normally be considered only after the external wiring, power, ground, connectors, relays, and controlled components have been properly tested.
Because Toyota uses different secondary air injection configurations across models and engine generations, the exact cause of P0418 must be established from vehicle-specific diagnostic information. The most effective approach is to trace the circuit from the ECM command through its power supply, relay, wiring, connector, and controlled component rather than replacing expensive parts based solely on the stored code.
How to Diagnose Toyota P0418
Diagnosing Toyota P0418 correctly requires tracing the Secondary Air Injection System as an interconnected electrical circuit rather than assuming that the pump or switching valve has failed. The first step is to confirm the exact factory definition of P0418 for the specific Toyota model, model year, engine, and emissions configuration. This matters because Toyota has used different system designs and control strategies across its vehicle range, so the relevant component and circuit should always be identified from the vehicle-specific service information and wiring diagram.
Once the code definition is confirmed, a scan tool should be used to retrieve all stored, pending, and history diagnostic trouble codes. Freeze-frame data can provide useful context by showing the operating conditions under which the ECM detected the fault. Related codes should not be ignored because another electrical or emissions code may identify a common power supply, ground, communication, or wiring problem. If P0418 is intermittent, examining when and under what conditions the code returns can be particularly valuable.
The physical inspection should then focus on the secondary air injection pump, switching valves, relays, fuses, wiring harnesses, connectors, and grounding points relevant to the vehicle. The technician should look for damaged insulation, melted wiring, corrosion, moisture intrusion, loose terminals, poor pin contact, and signs of previous repairs. Components located in areas exposed to heat, water, road contamination, or engine vibration deserve particular attention because environmental damage can create intermittent electrical resistance that is difficult to identify visually.
Electrical testing should follow the Toyota wiring diagram and specified test procedures. Power supply, ground integrity, continuity, resistance, voltage, and voltage drop can be measured at the appropriate points in the circuit. Where supported by the diagnostic equipment, active tests and live data can help determine whether the ECM is commanding the system and whether the relevant component responds correctly. A component that receives the correct command and power but fails to operate may require further component-level testing, while an incorrect signal at the control side can redirect the diagnosis toward wiring, relay, connector, or ECM control issues.
Only after the external circuit and controlled components have been properly evaluated should the ECM or other expensive components be considered. After the confirmed fault is repaired, the diagnostic codes should be cleared and the vehicle operated under the conditions required by the Toyota diagnostic procedure. A follow-up scan is important because a successful repair should be verified by confirming that P0418 does not return and that the secondary air injection system completes its applicable self-monitoring cycle.
How to Fix Toyota P0418
Fixing Toyota P0418 starts with identifying the actual fault in the Secondary Air Injection System rather than replacing components based only on the diagnostic trouble code. Because P0418 indicates a problem associated with the system’s electrical control circuit, the correct repair depends on what testing reveals. A damaged wire, poor connector connection, failed relay, inadequate power supply, or defective switching component can require very different repairs even though the same code is stored in the ECM.
If testing identifies an open, short, damaged section, or excessive resistance in the wiring harness, the affected circuit should be repaired using appropriate automotive-grade wiring and proper terminal connections. Corroded or loose connectors may require terminal repair or connector replacement rather than simply being cleaned and reconnected. Any repaired wiring should be protected against heat, moisture, vibration, and abrasion so that the original electrical problem does not return.
When the diagnosis confirms a faulty fuse or relay, the failed component should be replaced with the correct specification for that Toyota application. However, a blown fuse should not simply be replaced without investigating why it failed. An excessive electrical load, short circuit, seized secondary air injection pump, or damaged wiring could cause the fuse to fail again. Similarly, replacing a relay without verifying the control and load circuits may leave the underlying problem unresolved.
If the secondary air injection pump or switching valve fails testing, replacement may be necessary. The correct procedure depends on the specific Toyota configuration and may involve additional inspection, installation procedures, or system initialization. In some applications, a brake-like diagnostic mindset is especially useful because the electrical command, power supply, mechanical operation, and feedback must all agree for the system to function correctly.
An ECM fault is possible but should generally be considered only after the related power, ground, wiring, connectors, relay, and controlled components have been verified. Replacing an ECM without proving that it is the source of the fault can create significant unnecessary expense. After the repair, the stored codes should be cleared and the vehicle tested under the operating conditions specified for the system. A final scan should confirm that Toyota P0418 remains absent and that the Secondary Air Injection System can complete its required monitoring cycle.
Toyota P0418 Repair Cost
The repair cost for Toyota P0418 can vary considerably because the code identifies an electrical fault within the Secondary Air Injection System rather than specifying one failed part. The final price depends on the Toyota model and engine, the exact circuit affected, labor rates, diagnostic time, replacement parts, and whether additional procedures such as system initialization or verification are required after the repair.
A relatively simple wiring, connector, fuse, relay, or ground problem is generally less expensive to correct because the required parts may be inexpensive and the repair can often be completed without replacing a major emissions component. However, intermittent electrical faults can increase labor time because the technician may need to reproduce the condition and perform voltage, resistance, continuity, or voltage-drop tests at several points in the circuit.
If testing confirms a failed switching valve or another secondary air injection component, the cost will typically increase because parts and installation time become more significant. A failed secondary air injection pump can be considerably more expensive than a basic electrical repair, particularly when access is difficult or additional components must be removed. In the least common situations where diagnosis confirms an ECM-related problem, the total repair cost can increase further because module replacement may involve programming or configuration procedures.
For this reason, an accurate Toyota P0418 repair estimate should be based on diagnosis rather than the code alone. Paying for proper electrical testing at the beginning can actually reduce the total repair bill by preventing unnecessary replacement of an expensive pump, valve, or ECM. Once the root cause has been confirmed, the repair facility can provide a much more reliable estimate based on the specific vehicle and required procedure.
Can You Drive With Toyota P0418?
Whether you can drive with Toyota P0418 depends on the vehicle’s symptoms and whether any other diagnostic trouble codes are present. Because P0418 is associated with the electrical control circuit of the Secondary Air Injection System, an isolated fault may not immediately cause a major change in normal engine operation. The Toyota may start, accelerate, and cruise normally while the Check Engine Light remains illuminated. In this situation, a short drive to a qualified repair facility may be possible, but the fault should not be ignored.
The secondary air injection system primarily supports emissions control under specific operating conditions, particularly during cold starts. A failure in this system does not necessarily mean that the engine has lost its ability to operate. However, continued driving with the Check Engine Light illuminated can make it harder to identify new problems if additional faults develop. An emissions-related fault may also prevent the vehicle from completing its required OBD-II readiness monitors, which can become important during emissions testing or vehicle inspection where applicable.
More caution is necessary if P0418 appears together with rough running, stalling, difficult starting, reduced engine performance, unusual electrical behavior, or multiple warning lights. These symptoms can indicate that the problem extends beyond the secondary air injection circuit. A persistent electrical fault can also affect other components if there is an underlying short circuit, unstable power supply, or damaged wiring.
If the Toyota develops serious drivability problems or shows signs of a broader electrical or engine-management failure, continuing to drive should be avoided until the vehicle has been inspected. The safest approach is to treat Toyota P0418 as a fault that requires timely diagnosis, even when the vehicle appears to drive normally. Once the underlying cause has been repaired, clearing the code and confirming that the system completes its diagnostic monitoring cycle provides a more reliable indication that the problem has actually been resolved.
Toyota P0418 vs. Related Secondary Air Injection Codes
Toyota P0418 is easier to understand when it is evaluated alongside other diagnostic trouble codes from the Secondary Air Injection System. A single code may identify an electrical control problem, while additional codes can reveal whether the fault also affects the pump, switching valve, airflow, or another part of the emissions control system. For this reason, clearing P0418 without investigating related codes can result in an incomplete repair.
Codes associated with the broader secondary air injection system can point toward different stages of the system’s operation. A code indicating insufficient or excessive secondary air flow may suggest that the system is not delivering the expected amount of air, while a circuit-related code can direct attention toward electrical control. When P0418 appears together with other secondary air injection codes, the combination can provide more useful diagnostic information than any individual code considered in isolation.
The timing of the codes is also important. If P0418 is stored together with power supply, ground, or communication faults, the electrical problem may be affecting several systems simultaneously. In contrast, if the secondary air injection pump or switching valve has a dedicated fault alongside P0418, the technician may need to determine whether the component failure caused the circuit fault or whether both codes resulted from a common wiring or power problem. Freeze-frame information and the order in which the codes appeared can help establish this relationship.
Toyota owners should therefore avoid treating every stored code as an independent component failure. A damaged harness, corroded connector, failed relay, unstable voltage supply, or poor ground can create multiple diagnostic symptoms across the same system. The most effective diagnosis follows the electrical and functional relationships between the codes, rather than replacing parts according to the number of codes displayed.
Because Toyota secondary air injection systems differ between models, engines, and model years, the exact relationship between P0418 and other DTCs should be confirmed using the appropriate factory diagnostic information. This vehicle-specific approach helps distinguish the primary fault from secondary codes and reduces the risk of unnecessary repairs.
How the Toyota Secondary Air Injection System Works
The Toyota Secondary Air Injection System is an emissions control system designed to help reduce pollutants during specific engine operating conditions, especially immediately after a cold start. When an engine first starts, the air and fuel mixture, combustion temperature, and catalytic converter temperature are not yet at their most efficient operating conditions. The secondary air system addresses this part of the emissions cycle by introducing additional fresh air into the exhaust system, providing oxygen that supports the oxidation of unburned hydrocarbons and helps the catalytic converter reach its effective operating temperature more quickly.
The system operates through coordinated control between the ECM and several electrical and mechanical components. When the required operating conditions are detected, the ECM can command the appropriate relay or control circuit, allowing the secondary air injection pump to operate. Air is then directed through the applicable switching or air injection valves toward the exhaust system. Depending on the Toyota application, the system architecture can differ, meaning the exact arrangement of pumps, valves, relays, sensors, and control circuits should be confirmed using the vehicle-specific wiring diagram and service information.
Electrical control is particularly important because the ECM must determine whether the commanded components respond correctly. Power supply, ground circuits, wiring harnesses, connectors, relays, and control signals all form part of the system’s operating chain. If one part of this chain develops an open circuit, short circuit, excessive resistance, poor terminal connection, or unstable voltage condition, the system may fail to operate as commanded. Toyota P0418 can therefore represent a problem within this broader electrical relationship rather than a simple mechanical failure.
The ECM also uses diagnostic logic to monitor system operation. Depending on the specific Toyota configuration, it may evaluate electrical conditions, component response, airflow-related information, or other feedback associated with the secondary air injection process. This explains why diagnosing P0418 requires more than listening for the pump or checking whether one valve moves. The technician needs to determine whether the ECM command, electrical circuit, controlled component, and system response are consistent with the expected operating conditions.
Understanding this relationship is essential when diagnosing Toyota P0418. The code sits within a network that connects the ECM, relay and power supply, wiring, secondary air injection pump, switching valves, and exhaust emissions system. Identifying where that chain breaks is what separates an accurate repair from unnecessary replacement of expensive components.
When Toyota P0418 Requires Major Repair
Toyota P0418 does not automatically mean that the vehicle needs a major repair. In many cases, the underlying problem can be resolved through a relatively straightforward electrical repair involving a damaged wire, poor connector, failed relay, blown fuse, or defective ground connection. The key distinction is whether testing identifies a localized circuit problem or confirms a failure of a major component within the Secondary Air Injection System.
A more substantial repair may become necessary when the secondary air injection pump, switching valve, or another major system component fails its electrical or functional tests. A pump that has an internal electrical failure, excessive current draw, or mechanical seizure may require replacement. Likewise, a switching valve that does not respond correctly to the commanded signal may need to be replaced after its power supply, ground, wiring, and control circuit have been verified.
The ECM should normally be considered only after the rest of the circuit has been thoroughly tested. A control module can be expensive, and replacing it without confirming the fault can create unnecessary costs while leaving the original problem unresolved. A proper diagnosis should establish that the ECM has the required power and ground, that the wiring and connectors are intact, and that the controlled components respond appropriately before an ECM-related repair is considered.
Access can also influence whether a P0418 repair becomes substantial. Some Toyota configurations place secondary air injection components in locations where removal of surrounding parts is required, increasing labor time even when the failed component itself is straightforward to identify. After certain repairs, the vehicle may also require specific testing, initialization, or monitoring procedures before the repair can be considered complete.
The most important principle is that the size of the repair should be determined by evidence, not by the presence of Toyota P0418 alone. A confirmed circuit fault should receive a circuit repair, while a confirmed component failure should receive the appropriate component replacement. This approach protects the owner from unnecessary parts replacement and provides a much stronger chance of preventing the code from returning.
How to Prevent Toyota P0418 From Returning
Preventing Toyota P0418 from returning depends on correcting the original electrical or component failure completely rather than simply clearing the diagnostic trouble code. If a damaged wire, loose terminal, corroded connector, weak ground, or failing relay remains in the circuit, the ECM may detect the same abnormal condition again during a future monitoring cycle. A proper repair should therefore restore the circuit to the electrical and mechanical condition specified for the particular Toyota application.
The condition of the wiring and connectors deserves continued attention because the Secondary Air Injection System operates in the engine compartment, where heat, vibration, moisture, and contamination can gradually affect electrical connections. During routine maintenance or diagnostic work, signs of damaged insulation, corrosion, loose terminals, or previous poorly executed wiring repairs should be addressed before they develop into intermittent faults. Protecting repaired wiring from heat and abrasion can also reduce the likelihood of another circuit failure.
Stable electrical power is equally important. A weak battery, charging-system problem, or poor engine and chassis ground can create abnormal voltage conditions that interfere with electronically controlled emissions components. Maintaining the vehicle’s battery and charging system and ensuring that major ground connections remain clean and secure can help prevent electrical faults from affecting the secondary air injection circuit.
The secondary air injection components should also be maintained according to the requirements of the specific Toyota model. If the vehicle uses switching valves, pumps, or other components that are vulnerable to contamination or moisture, addressing the underlying cause of component deterioration is important. Replacing a failed component without identifying why it failed can allow the same condition to develop again.
After any repair, the most reliable prevention strategy is verification. The diagnostic codes should be cleared, the applicable system test or drive cycle should be completed, and the vehicle should be rescanned to confirm that P0418 does not return. When the repair restores the complete relationship between the ECM, electrical circuit, secondary air injection components, and emissions system, the likelihood of Toyota P0418 recurring is significantly reduced.
Frequently Asked Questions About Toyota P0418
What is Toyota P0418?
Toyota P0418 is an OBD-II diagnostic trouble code associated with a fault in the electrical control circuit of the Secondary Air Injection System. The exact factory definition and circuit configuration can vary by Toyota model, model year, engine, and market. The code should therefore be confirmed against the vehicle-specific service information before a component is replaced.
Is Toyota P0418 serious?
Toyota P0418 is not always an immediate drivability emergency, particularly when the vehicle starts and operates normally. However, it should not be ignored because the fault can prevent the secondary air injection system from operating correctly and may cause emissions-related diagnostic monitors to remain incomplete. If the code appears with rough running, stalling, multiple warning lights, or other significant symptoms, the vehicle should be inspected promptly.
Can I drive with Toyota P0418?
A Toyota with an isolated P0418 may remain driveable because the Secondary Air Injection System is primarily related to emissions control during specific operating conditions. However, continued driving is not a substitute for diagnosis. If the vehicle develops poor engine performance, stalling, unusual electrical behavior, or additional warning indicators, driving should be minimized until the underlying problem is identified.
What causes Toyota P0418?
Possible causes include damaged or open wiring, short circuits, excessive circuit resistance, corroded connectors, poor terminal contact, failed fuses or relays, power supply problems, weak grounds, defective switching components, or a problem with the secondary air injection pump. An ECM-related fault is possible in some applications but should generally be considered only after the external circuit and components have been tested.
Does Toyota P0418 mean I need a new secondary air injection pump?
No. P0418 identifies a detected fault within a control circuit and does not by itself prove that the secondary air injection pump has failed. Wiring, connectors, relays, fuses, grounds, and other control components should be tested first. Replacing the pump without confirming the fault can result in unnecessary expense.
Can a bad relay cause Toyota P0418?
A faulty relay can potentially cause P0418 when the relay is part of the relevant secondary air injection control or power circuit. A relay that fails to supply the expected voltage can prevent the controlled component from operating correctly. The relay should be tested according to the Toyota wiring diagram and specifications rather than replaced solely because the code is present.
Can low battery voltage cause Toyota P0418?
Unstable or insufficient system voltage can interfere with electronically controlled emissions components and may contribute to diagnostic faults. However, low voltage should be confirmed through electrical testing rather than assumed to be the cause. Battery condition, charging voltage, grounds, and circuit voltage should be evaluated together when an electrical DTC is present.
How much does Toyota P0418 cost to repair?
There is no universal repair price for Toyota P0418. A wiring or connector repair may be relatively inexpensive, while a failed switching component or secondary air injection pump can require substantially more parts and labor. Diagnosis, vehicle configuration, component accessibility, and any required initialization or verification procedures also influence the final cost.
Why does Toyota P0418 keep coming back after repair?
A recurring P0418 often indicates that the original fault was not fully resolved or that another related problem remains in the circuit. Intermittent wiring damage, poor connector contact, unstable voltage, inadequate grounding, or an incorrectly diagnosed component can cause the code to return. A recurring code should trigger a complete circuit diagnosis rather than another round of parts replacement.
A wheel speed sensor is not normally part of the Secondary Air Injection System, so it would not be an expected direct cause of P0418. However, other diagnostic codes can appear simultaneously because of separate faults or broader electrical problems. The complete set of stored codes should always be evaluated before deciding which fault is primary.
Does Toyota P0418 mean the engine or emissions system has completely failed?
No. Toyota P0418 does not mean that the engine or the entire emissions system has failed. It indicates that the ECM has detected a problem associated with a particular secondary air injection control circuit. The actual impact depends on the underlying fault, and accurate diagnosis is required to determine whether the problem is limited to wiring, a relay, a switching component, the air injection pump, or another part of the system.
Conclusion
Toyota P0418 is a diagnostic starting point, not an automatic instruction to replace the secondary air injection pump, switching valve, or ECM. The code points to a detected problem within the electrical control circuit of the Secondary Air Injection System, but the actual cause can vary significantly according to the Toyota model, model year, engine, emissions configuration, and market. Confirming the vehicle-specific factory definition should therefore be the first step before any component is replaced.
A proper diagnosis connects the entire system, including the ECM, relay, fuse, wiring harness, connectors, power supply, ground circuits, secondary air injection pump, and switching components. Symptoms such as a Check Engine Light, abnormal cold-start behavior, intermittent system operation, or additional emissions-related codes can provide useful clues, but they cannot identify the failed component by themselves. Electrical testing, visual inspection, scan data, freeze-frame information, and appropriate functional tests are needed to establish the root cause.
Repair costs can range from a relatively simple wiring or connector repair to a more expensive component replacement when testing confirms a failed pump or valve. The most cost-effective strategy is to diagnose the circuit before purchasing major parts. Once the confirmed fault has been repaired, clearing the DTC, completing the applicable drive cycle, and rescanning the vehicle helps verify that the Secondary Air Injection System is operating correctly and that Toyota P0418 does not return.
If your Toyota has stored P0418, do not rely on the code alone to determine what needs to be replaced. Use the code as the beginning of a structured diagnostic process, verify the exact system configuration, and address the confirmed root cause. This approach improves repair accuracy, reduces unnecessary expense, and provides the best chance of restoring the emissions system to proper operation.