ethanol causing false check engine lights?

[zzvyb6]

Well just in case its not an obvious vacuum leak, the most common cause of a check-engine light is loose or leaking fuel cap, spark plugs and the oxygen sensor.

 

[jonyyuma]

The oxygen sensor is supposed to be the most common culprit on a check-engine light.

 

[55acwd45]

We have a 2010 Cobalt that I suspect throws the CEL from poor fuel or ethanol.

Its the system too lean, bank #, sensor #. It only has 13,000 miles. Dealer couldn't find anything wrong with it but suggested a "routine maintenance" cleaning of the fuel system for ONLY $130 or so. Its not a flexfuel car. Lately the light has stayed off on its own. I've check the car over twice and so has the dealer and they have not found any problems. Adjusting the fuel trim would fix the problem.

Light was off for a while and we had some gas in a can for a month or so and my dad put the gas in the car and it turned the CEL on the next day. It was clean gas.

 

[PoorMansCat]

I have found that there are several stations here that sell NO ETHANOL fuel... I have started using that on my small engines.. All my carburetor issues and increased fuel consumption issues have since ceased.

 

[crazyal]

I had a Saturn that had the intake gasket start leaking. The CEL was giving an O2 sensor fail but it was also picking up on a #1 cylinder misfire. That made it real easy to find.

 

[LD1]

I had a Saturn that had the intake gasket start leaking. The CEL was giving an O2 sensor fail but it was also picking up on a #1 cylinder misfire. That made it real easy to find.

Now that you mention it, Dads 2002 SL1 did the EXACT same thing. SAME tw codes. O2 lean condition, and #1 misfire. But it was intermitten when the CEL would come on.

I did some googleing and that pointed me in the direction of an intake leak around #1 cylinder. Did the old "spray with carb clean test" and confirmed that yep, there was a leak.

This was last year or so. Replaced the intake and no trouble since:thumbsup:

 

[MyJoBota]

My suggestion would be to take it to a parts store like autozone and let them read the engine codes, sell you a bunch of parts that wont fix the problem and tell you how easy it is to replace them. After you are frustrated and about out of money take it to repairshop capable of diagnosing and repairing the car properly. That's how we roll in this neck of the woods.:laughing:

 

[PILOON]

Well just in case its not an obvious vacuum leak, the most common cause of a check-engine light is loose or leaking fuel cap, spark plugs and the oxygen sensor.

YEP!
Just 2 weeks back my check light went on and had me worried.
I tightened the fuel cap and the light went off.

 

[2manyrocks]

The truck check engine light is now off after I disconnected the battery. I drove it to town and back and so far no more light.

MyJoBota--I've been down that road with the protege before I posted here.

The good repair shop next to me sold out and the guy that took over wasn't good. He's out of business. So l have to go through these tips and see if I can find the problem with the Protege.

Thanks all.

 

[LD1]

The truck check engine light is now off after I disconnected the battery. I drove it to town and back and so far no more light.


Thanks all.

How were you abe to get it started with the battery disconnected:laughing::laughing:

Sorry, couldnt help myself.