Check engine light on and blinking when accelorating

Hello. When I was driving to school this morning my check engine light went on and I noticed that my car is running very rough (suddenly). I also noticed that the check engine light would blink when accelorating at a stop light then go solid again when driving. HELP! I drive long distances between school and work and I think I won’t be making it to work later due to this issue. This is a Saturn Ion II 2005 and gets regular maintanence on time.

If you want to avoid making the potential repairs much more expensive, you will get this car to a qualified mechanic today. A blinking CEL indicates engine misfire, and this can cause damage in more than one way if it is allowed to continue.

A steadily-illuminated CEL=go to a mechanic as soon as is convenient.
A blinking CEL=go to a mechanic today.

Even if the blinking is intermittent, that should be enough for you to interpret this as something that needs immediate attention.

From a distance, nobody can tell you what the source of the problem might be, and only someone who can read the trouble codes stored by the car’s OBD system and who is good at diagnosis (rather than just replacing parts) will be able to figure out the solution.

Jenn, The Rough Running And Blinking CEL Both Indicate An Engine Misfire.

This is a situation in which the car should not continue to be driven until the misfire problem is resolved. To drive it like this can lead to other serious problems, perhaps more serious than the one causing this problem.


Thank you for your feedback. I will be going straight to my mechanic after school.

“This is a Saturn Ion II 2005 and gets regular maintanence on time.”

You didn’t indicate how may miles are on this Saturn, but since this vehicle is well cared for it’s possible that the problem is relatively minor.

Please do a favor and let us know what is found and what solution is reached.


@jennlafren–I’m very glad that you are taking this seriously.

As a courtesy to us, so that we can help as many people as possible, could you return to give us your mechanic’s diagnosis of the problem?

It is just over 100,000 miles and I will keep you posted as to the outcome of this situation.

Well. Getting back to you on the diagnosis of my car trouble yesterday. NOT GOOD. Apparently Cylinder #3 had a bad ring and lost compression, my engine is dying and it’s time to go car shopping. I bought the car a year ago and unfortunately it didn’t last me as long as I thought it would.

I’m sorry to hear about the bad news regarding your car.

Regarding shopping for a new(er) car, I strongly urge you to have your “finalist” for purchase inspected by your mechanic prior to purchase. That way, you can–hopefully–be spared from buying a car that you will later regret. This will probably cost you ~$100, but that would be money well-spent if it saves you from thousands of $$ in later repair costs.

A seller who balks at having a vehicle inspected may well be trying to conceal a major defect, so it is probably best to move on to a different car if it is not possible to have your own inspection performed prior to purchase.

Please read through all 4 pages of this recent thread regarding the pre-purchase inspection of used cars:

@Jenn, you might also consider getting a second opinion on your Saturn’s problem. Did the mechanic who gave you that diagnosis have other cars for sale? If so, they have a genuine conflict of interest. Even your local parts store can read the On Board Diagnostics (OBD) codes for you for free. Do you have an AutoZone, O’Reilly’s, or Advanced Auto Parts store in your area?

I was about to walk you thru why you may be having a misfire… Modern trannys HATE when the engine is misfiring…and so do I. The Misfire is the cause of the Blinking CEL…it freaks out the tranny…and that makes the cel blink Anyway you say you have a “BAD RING” in cyl number 3?

I would get another opinion…unless this guy is REALLY GOOD. If he went thru a lot of testing with the cylinder head and leak down tests ets…then maybe he is on point… I would suspect a faulty or hung up valve maybe even a head gasket breech before anything else.

But a Bad Ring? Thats pretty specific…and could be the problem… I just don’t know what tests he did…and he would need to do quite a few of them to be as specific as they have been. I’m doubting this diagnosis.simply because its difficult to make that call of one bad ring…if one is bad…they all go bad usually. Id suspect a valve FAR before a ring… Thats my 2 cents and 27 yrs experience talking.


Agreed Blackbird, and better said than my answer.

Did this mechanic provide the cylinder compression numbers for you? If not, this is a mistake that should be avoided because they should always be put down in black and white.

An engine car run fine with a bad ring. If the engine were fine one minute and missing badly the next the only way a ring would cause this would be a sudden catastrophic piston/ring failure (extremely low chances of this) or the spark plug fouled from oil consumption past the ring.

If you can get the compression numbers, find out if the plug was oil fouled, and post the info we will have a look at what’s there.
Other than that I might suggest another opinion; just in case. The reason why is I’ve seen engines diagnosed as bad when the cause some something actually trivial and cheap.
I vaguely remember one engine being diagnosed as needing a valve job when the cause was a popped 25 cent fuse for one bank of fuel injectors and another diagnosed “valve job” was due to a broken vacuum line… :frowning:

Thank you for your feedback. I will look into getting a second opinion. He did a free diagnostics and didn’t even provide a printout of the report. I will look into this further and keep you posted.

Some years ago, my DIL’s car wouldn’t turn over. A mechanic told her the engine was frozen and needed a different engine. A mechanic from the Mechanics Files on this board discovered the air conditioning compressor was frozen. He took the belt off and she drove the car home. Yes, second opinion or more details.

Compression test
wet and dry
provide numbers

fuel pressure good?
spark okay?