A new light on your dashboard? You don’t understand why it doesn’t go out… It’s normal, a vehicle is complex and there are many reasons why a light may come on. If your glow plug light comes on while driving your car, it may indicate several concerns. In this article, we will do everything we can to help you see things more clearly. First, we will see how the preheating light on your car works, and then the different ways it lights up when you are driving

glow plug light on when I drive

What is the purpose of my car glow plug light?

The main purpose of the engine glow plug light, which is generally represented by a yellow coil, is to ensure that your glow plugs are working properly. Indeed, it must light up when you switch on your car to tell you that they are heating the intake air in your cylinders and must go out after a few moments when the engine is running. This preheat light is therefore not supposed to stay or come on while driving with your vehcile. However, if it comes on while driving, it may show several failures, we will try to describe the main ones.

glow light plug comes on when I drive

What to do if the glow plug light comes on while driving on my car?

A glow light that comes on while driving on your car or at any other time other than when the engine is started is intended to alert you to a fault other than your spark plugs, we will look at this now. In any case, a switch to the diagnostic tool will allow you to carefully interpret the reason for the ignition of your glow light.

My car glow light comes on and I’m experiencing a loss of power

The first possibility is that you notice that your glow plug light comes on while driving your car and that you also experience a loss of power. In this case, several problems can explain its appearance. Here is a list of the main reasons:

  • Problem of EGR valve, indeed, if you suffer a loss of power, it is possible that your EGR valve is clogged, in this case, it is logical that your preheat light comes on while driving on XXX because it is one of the failures of which it is supposed to warn you. Have the status of your valve checked
  • Problem related to the turbo overflow valve, in this situation the ECU can no longer manage the turbo intake pressure, which can lead to turbo boost and a disturbance in the operation of the turbo.
  • Problem related to the injection, either an injector that has seized up or the injection pump that is damaged by filings or other possible foreign bodies that disturb its proper functioning.
  • Finally, the last problem that could lead to a glow indicator light on your car coupled with a loss of power, is that your fuel filter is too dirty, you should feel jerks because of a bad fuel flow in the engine.

My glow plug light comes on or is flashing but no difference on the performance of my car

Finally, we’ll give you the reasons for a glow plug light that comes on on your car without you feeling any difference in power or vehicle behaviour. In general, this is an electronic fault:

  • Glow plug relays or fuses to be replaced, test and replace if necessary.
  • A contactor/potentiometer on one of your pedals (brake, accelerator or clutch) has failed, often a simple de-seizure will be enough to solve the problem.
  • You have a false contact somewhere in your electrical circuit, test the other options first because it is not easy to find it alone, we advise you to go to your mechanic.
  • Faulty injection pressure sensor, ECU error