Glow Relay Stuck On Kia Optima? Common Reasons 

Do you have some concerns with your glow relay stuck on Kia Optima?

If so, then you may be concerned about what to do next. It can be a concerning problem, particularly because it helps minimize emissions. Thus, it makes your vehicle more eco-friendly.

When you look at modern-day diesel vehicles with the ones produced decades ago, it may be astounding to see the differences in the composition and performance. This is why with the introduction of the glow plug technology, this makes the emissions from diesel vehicles much less. 

Now, you may be asking what to do with a glow relay stuck on in your Kia Optima. If this is the issue you are experiencing, keep reading to understand why it happens.

glow relay stuck on kia optima

Glow Relay Stuck On Kia Optima

The glow plug is a control unit that makes use of a glow plug relay. This is used for switching your current for glow plugs – for turning them on and off. When you have many glow plugs that are monitored by your control unit, then you also need a higher current for it. 

So, when there is a need to minimize the current required, glow plugs are distributed across the two circuits, which is with the two glow relays. This is used mostly in older types of glow plug systems.

Now, to understand why your glow relay may be stuck on the Kia Optima, it is good to understand what actually happens upon starting your diesel vehicle. 

First, you turn your key in your ignition, which then starts your vehicle. Afterwards, the glow plug control unit will then analyze the input from your ECU in determining the electric current, timing, and also the duration needed by your glow plugs.

Next, this sends electric current to your glow plugs. This is what causes the glowing effect. Next up, there is a compression of the intake air, and this causes the fuel to be sprayed onto the glow plugs’ hot tips.

Next, combustion begins soon after the injected fuel combines with this compressed air in your warm cylinder. 

Your glow plug control unit makes sure that the glow plugs remain on for a certain period after starting your engine. This is a way to ensure an optimal fuel combustion while at the same time reducing emissions.

Not many people are well aware of how glow plugs work – and even what these are. But it is important to note that it is a key component of the engine. When the outdoor temperature is cold, and you turn the ignition on to start the vehicle, your engine tends to struggle with turning over and firing up. 

When it comes to diesel engines, these may have a difficult time since your cylinder head and block tend to absorb the compression heat required for an ignition to happen.

Glow plugs are basically metal components with a pencil shape. These heat your engine up quickly. The glow occurs when the tips’ heating element becomes electrified when your engine is not adequately warm to initiate a combustion. This also speeds up the process of igniting the fuel.

As time passes by, the glow relay may wear out and fail. So, when the colder weather starts, you may also begin to notice that your vehicle is not performing as it used to. This is why if you think it is an issue with your glow relay, you need to know how to diagnose and troubleshoot this component to prevent further problems.

There are many reasons why your glow relay may fail. For example, it could be a simple wear and tear problem. When exposed to extreme climates, in combination with some fluctuations to the electrical currents, as well as misfiring injectors, the glow relay may further become damaged. 

This is why to avoid this issue, you need to keep your vehicle well-maintained. Make it a point to perform routine maintenance. If you notice some issues, you should get it serviced and fixed sooner than later to prevent more problems from developing.

Now, there are a few signs of your glow relay failing.

The most common is a warning on your dashboard. When you notice the check engine light turn on, or you see the glow plug dash light switch on or flash, this may mean that there is a problem with the glow plugs. 

So, if you are starting your vehicle in a colder weather, you may see the glow plug dash light switch on for only a few seconds as it warms the engine up. 

However, if the light starts to flash or does not come on, it means there is a problem. You may  also want to check if your engine is starting to have issues with starting. This is another common symptom of a failing glow relay, especially in a cold morning.

If you notice white smoke coming out until your engine warms, your injection pump or injection timing may be acting up. These components both impact the glow plugs, as well as the relay. It is also possible that the white smoke may clear out when your vehicle has warmed up. But this is not a condensation that normally happens.

Lastly, check for hesitation or rough idling when you have just started your car. These symptoms are also possible glow plug or relay issues, as well as an injector concern that need to be checked. 

Wrap Up

If you notice the symptoms above, or the glow relay is stuck on in your Kia Optima, then it is best to have your car inspected by a specialist. Make sure you take your vehicle to a specialist or dealer, so it can get serviced sooner than later.

Do keep in mind that small issues can quickly escalate into something big. This is why before these all happen, you need to have the problem addressed before it is too late.

2 thoughts on “Glow Relay Stuck On Kia Optima? Common Reasons ”

    • Hi Betty,

      The exact location and appearance of the glow relay may vary depending on the specific model year of your Kia Optima. However, in general, the glow relay is typically located in the engine compartment.

      To locate the glow relay, you can follow these steps:

      Open the hood of your Kia Optima and secure it in place.

      Look for the fuse box or relay box in the engine compartment. It is usually a black plastic box with a removable lid.

      Check the inside of the lid or the fuse box cover for a diagram or label that indicates the location of the glow relay. It may be labeled as “Glow Relay,” “Glow Plug Relay,” or something similar.

      Once you have identified the glow relay, you can visually inspect it. It is typically a small rectangular or square-shaped component with electrical connectors on the top or side.

      Please note that the specific location and appearance of the glow relay may vary depending on the year and engine configuration of your Kia Optima. Consult the vehicle’s owner’s manual or seek professional assistance if you’re having trouble locating the glow relay.

      Good luck!


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