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?

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・Fair and transparent pricing

Get a quote

What others are asking

Q: Loud buzzing before the engine cranks

This sounds like the starter solenoid - the part of the starter assembly which acts as a high-current power relay for the starter motor - has worn or burned contacts. This makes it tougher to get adequate power to the...

Q: Car stopped in middle of highway - 2016 Fiat 500

Hello. This is a new problem and there seems to be no information on this issue yet for your vehicle. I suggest having the computer tested to see if codes were set and have them diagnosed. Contact your local dealer...

Q: Steering wheel hard to turn at times

Hello. When the steering becomes hard to turn at slow speeds then it is typically caused by a bad hydraulic pump, which would need to be replaced. However, I would first check the fluid in it as low fluid will...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
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...