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

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: 2013 BMW 650i shakes, loses power, warning lights come on

Hey there, thanks for writing in about your 2013 BMW 650i. Solutions have been found to problems similar to yours, but two vehicles with the same symptoms may still require different repairs. Your best bet is to have an experienced...

Q: Radiator leak

If the leak is of any significance, it's probably not drivable simply because the water will leak out too quickly unless you are talking about a very, very tiny pinhole. If the leak is visible and accessible, there are products...

Q: Windshield wipers don't work

There are a couple possibilities. The electric wiper motor has failed or blew a fuse, or the problem is in the wiper transmission linkage. When the plastic parts of the transmission are worn, the linkage can come apart. Grab a...

Related articles

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...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...