Skip the auto shop - Our mechanics make house calls

What Does the Diesel Engine Pre-Glow Warning Light Mean?

What Does the Diesel Engine Pre-Glow Warning Light Mean?

Due to the nature of diesel engines, they require some extra help when first starting up at a cold temperature. The glow plug is a heating element that is activated during startup when the temperature of the engine is too low. It raises the temperature inside the cylinders to facilitate in pressurizing and detonating the diesel fuel. The system typically makes the driver wait around 10 seconds while the plugs warm up the engine. Once the correct temperature has been achieved, the computer will then let the driver start the engine.

What the diesel engine pre-glow light means

Normally, the glow plug indicator light will come on only when the engine is cold. Typically, this light flashes only when an issue has been detected.

The most common reason to replace glow plugs is age. Over time, after repeated warm up cycles, the glow plugs age and are not able to produce any heat. Replacing any malfunctioning glow plugs should get rid of any issues you are having. If a new glow plug doesn’t remedy the problem, take a look at other parts of the circuit, mainly the timer. The timer’s job is to turn the plugs off once the correct temperature has been reached. A faulty timer may keep the plugs on for too long, wearing them out, or even not turn the plugs on at all.

If a fault has been detected, the computer will save a code in its memory to help diagnose the issue. Have a certified technician hook up a scan tool to your car to read this code.

Is it safe to drive with the diesel engine pre-glow light on?

Some vehicle engines cannot even be started until the glowplug light has turned off, therefore preventing the drivers from starting the engine too soon. You should always wait for the light to shut off before attempting to start the engine. Being a little patient will help keep your engine going strong in the long run.

Our certified technicians are always available if you ever require assistance identifying glow plug issues.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
How Long Does a Fuel Filler Neck Last?
Getting gas from the pump to your gas tank is the only way to keep a car going. The fuel filler neck is a metal tube that is welded to the...
P0222 OBD-II Trouble Code: Throttle/Pedal Position Switch/Sensor B Circuit Low Input
P0222 code definition Throttle/Pedal Position Switch/Sensor B Circuit Low Input What the P0222 code means The manufacturer specifies a range of acceptable voltage to be produced from the throttle position...


Related questions

Q: Where is the fuel gauge located?

It’s important that you know how much gas is in your car at all times. The fuel gauge gives you a pretty accurate estimate. However, understand that it is not 100% accurate (no fuel gauge displays anything but the approximate...

Q: When weather is cooler my truck strugles to start

You may have some carbon build up in the combustion chambers and need to have the engine decarbonized. You could also use an octane booster if you have issues after new glow plugs are installed. Once the glow plugs get...

Q: The ASR light came on and the car went into limp mode - (the gas pedal work from the middle of pressing it).

Hi there. The ASR light is on for an issue with the throttle pedal position sensor located on the gas pedal. You may be able to reset the parameters without replacing any parts. Perform the following to reset the lights...