Skip the auto shop - Our mechanics make house calls

Q: Preglow indicator light on

asked by on

The preglow indicator light came on in my car. It is illuminated in orange and it turns on when I turn the key before the engine starts running. What does this light indicate? Are there any issues that might damage the car?

A: Your car has a diesel engine. Diesel engine...

Your car has a diesel engine. Diesel engines have no spark plugs, they rely on ultra high compression of the fuel, which is injected at precisely the highest air pressure in the cylinder, to ignite on it's own based on the rise in temperature of the compressed air. When a diesel engine is cold this is more challenging. Glow plugs, tiny electrical coils inside the cylinder, heated by the car's battery prior to starting, help the engine come up to operating temperature so that normal compression-based ignition occurs. The orange light you describe indicates that the glow plugs are coming on as designed. If you are experiencing and performance issues, have a certified technician inspect the car to pinpoint the issue.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: What does the high-beam on light mean?

The high-beam on light is located on your instnrument panel. When the light is illuminated, the high-beams are currently on. The light will disappear when the high-beams are turned off.

Q: Driver's seat not moving

The "thing under the seat" could be the seat frame, or power motor assembly. The lower power seat is a separate part from the seat itself and may need to be replaced. The power seat frame is not a serviceable...

Q: We have charged both batteries 100%, replaced the voltage regulator and altenator, but when we use the lights the battery drains

Hi, thanks for writing in. It sounds like the wire from the batteries to the alternator could be faulty. If this wire is not performing as it should the voltage from the alternator will never reach the batteries to charge...

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...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.