Your diesel vehicle is equipped with glow plugs, and also with a Glow Plug Light that will either come on and stay on, or flash or blink when a fault is detected by the ECU (engine management unit). When the Glow Plug Light comes on, the ECU stores information about the condition that has caused it to come on. A qualified mechanic who has a code reader that is suited to your particular make and model of vehicle can retrieve this information, and then make a diagnosis of the problem and recommend a course of action.
So, can you drive safely with the Glow Plug Light on? It depends on the nature of the problem. Sometimes, when the Glow Plug Light comes on, the engine in your vehicle will go into “safety” mode, in order to prevent any damage to the engine. If this should occur, you might perceive a drop in performance. This is likely not a big deal if you’re just booting around town, but it could present a safety issue if it occurs when you are performing a maneuver like passing or merging on the highway. Here is what you need to do.
Get a diagnostic check as soon as possible in order to find out just what the problem is and how to correct it. You don’t want to leave this to guesswork. Much of the time, the problem can be attributed to faulty crank sensors or cams, but there are also other things that can cause the Glow Plug Light to come on.
If you must continue to drive, make sure to take it easy. It would probably be best to avoid highway driving.
Do not assume that the problem will just go away on its own – it won’t. The Glow Plug Light came on for a reason, and until you find out what that reason is and have it corrected, it is going to stay on.
You can probably drive safely with the Glow Plug Light on as long as you take it easy. But you do need to get it checked out. Always remember, your warning lights are trying to tell you something, and determining whether the message is serious or of little consequence is best left up to a qualified mechanic.
This article originally appeared on YourMechanic.com as Is It Safe to Drive With the Glow Plug Light On? and was authored by Valerie Johnston.