Odd Engine Warning
Thread Starter
Pro
Joined: Jul 2018
Posts: 609
Likes: 591
From: Norman, OK
Odd Engine Warning
Driving to work this morning and my check engine light blinked on and off for around a minute then stayed off. I was going over a slightly bumpy section of road and thought maybe the engine's knock-sensor was confused. No issues in the 5 minutes after it stopped. Has anyone encountered an issue like this? I have a scangauge at home so I'll scan and see if anything popped up.
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Joined: Jun 2001
Posts: 18,599
Likes: 3,951
From: Jacksonville Florida BWO Dayton, Cincinnati, Bloomsbury NJ, Cincinnati
2015 C7 of the Year Finalist
A flashing CES is usually an 0300 code for a crapful of misfires in the engine.
Light Flashing: A misfire condition
has been detected. A misfire
increases vehicle emissions and
could damage the emission control
system on the vehicle. Diagnosis
and service might be required.
To prevent more serious damage to
the vehicle:
. Reduce vehicle speed.
. Avoid hard accelerations.
. Avoid steep uphill grades.
. If towing a trailer, reduce the
amount of cargo being hauled as
soon as it is possible.
If the light continues to flash, stop
and park the vehicle. Turn the
vehicle off, wait at least 10 seconds,
and restart the engine. If the light is
still flashing, follow the previous
steps and see your dealer for
service as soon as possible.
Elmer
Light Flashing: A misfire condition
has been detected. A misfire
increases vehicle emissions and
could damage the emission control
system on the vehicle. Diagnosis
and service might be required.
To prevent more serious damage to
the vehicle:
. Reduce vehicle speed.
. Avoid hard accelerations.
. Avoid steep uphill grades.
. If towing a trailer, reduce the
amount of cargo being hauled as
soon as it is possible.
If the light continues to flash, stop
and park the vehicle. Turn the
vehicle off, wait at least 10 seconds,
and restart the engine. If the light is
still flashing, follow the previous
steps and see your dealer for
service as soon as possible.
Elmer
Thread Starter
Pro
Joined: Jul 2018
Posts: 609
Likes: 591
From: Norman, OK
A flashing CES is usually an 0300 code for a crapful of misfires in the engine.
Light Flashing: A misfire condition
has been detected. A misfire
increases vehicle emissions and
could damage the emission control
system on the vehicle. Diagnosis
and service might be required.
To prevent more serious damage to
the vehicle:
. Reduce vehicle speed.
. Avoid hard accelerations.
. Avoid steep uphill grades.
. If towing a trailer, reduce the
amount of cargo being hauled as
soon as it is possible.
If the light continues to flash, stop
and park the vehicle. Turn the
vehicle off, wait at least 10 seconds,
and restart the engine. If the light is
still flashing, follow the previous
steps and see your dealer for
service as soon as possible.
Elmer
Light Flashing: A misfire condition
has been detected. A misfire
increases vehicle emissions and
could damage the emission control
system on the vehicle. Diagnosis
and service might be required.
To prevent more serious damage to
the vehicle:
. Reduce vehicle speed.
. Avoid hard accelerations.
. Avoid steep uphill grades.
. If towing a trailer, reduce the
amount of cargo being hauled as
soon as it is possible.
If the light continues to flash, stop
and park the vehicle. Turn the
vehicle off, wait at least 10 seconds,
and restart the engine. If the light is
still flashing, follow the previous
steps and see your dealer for
service as soon as possible.
Elmer
Team Owner
Joined: Sep 2000
Posts: 25,004
Likes: 2,706
From: Far NW 'burbs of Chicago
St. Jude Donor '13
On a group road trip in the boonies last year, our CEL came on steady for about 10 seconds, then flashed for about 5 seconds, then went out.
Engine running fine, no other indication of problem.
So we drove another 500 miles on that trip home. Several people here said I was crazy for continuing.
Took it to the dealer at home, they said there was the 0300 code. I told the Tech how it had gone for us, he said to keep driving and not worry unless something happens again. That was about 3k miles ago, still running great.
Engine running fine, no other indication of problem.
So we drove another 500 miles on that trip home. Several people here said I was crazy for continuing.
Took it to the dealer at home, they said there was the 0300 code. I told the Tech how it had gone for us, he said to keep driving and not worry unless something happens again. That was about 3k miles ago, still running great.
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I have heard that a check engine is usually related to an emissions issue, and perhaps some bad gas did cause the light to temporarily come on. Hopefully it was just a one time thing.
Thread Starter
Pro
Joined: Jul 2018
Posts: 609
Likes: 591
From: Norman, OK
Might have been. I always get 100% gas at Conoco and had never seen any issues before. Drove again today without issue so I'll just keep an eye out if it happens again and keep on driving until then.
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From: Bonneville Salt Flats
I've had similar (after getting "foreign" gas while on the road) with my C5 many years ago, but not in the past 4+ years with my C7. I agree, such is no reason to panic, and the only reason you even "know" about it is the sophisticated ( 
) electronics. 
) electronics.
Team Owner
Joined: Jul 2004
Posts: 28,429
Likes: 3,279
From: Hartford WI
Sensor is a microphone set to pick up sounds at a particular frequency. That your car happens to vibrate at that specific frequency when it goes over the road is pretty tough to believe.