ash_cpe

Hi everyone, my car has about 29k miles and I am getting Check engine light every time gas tank gets below 1/3 of it. I took it to the dealer twice now and every time they say "gas cap was opened while the vehicle was running". And that never happened.

Any advice or experiences can you guys share before I take it to the dealer next week?

Thank you.

ImInPA

The cap itself likely is leaking around the seal.

ash_cpe

Thanks ImInPA, dealer tested cap and saw no issues with it... And why it just happens when fuel is low?

ImInPA

perhaps you have a bit of water or other contaminants in the bottom of your tank. I would by a can of Sea Foam and dump it into a full tank and run it down. You may have to do this a couple times. I had this happen on a Volvo some years back. Water can condense on the inside of the tank when conditions allow it. Sea Foam will bind to the water and get it out of the tank. It is available at most Auto stores.

ash_cpe

Hmm, how could water get in there? I used to use Costco gas and i am using Shell V-Power after 1st time I had the check engine light on.

ImInPA

If the tankis not kept completely full, water can condense (sweat) on the inside of the tank. In diesels, there is actually a water separator to remove the excess water. In any event, Sea Foam is a great product suould your issue be related to fuel contamination. I still think the likely culprit is the gas cap or possibly an O2 sensor somewhere. It the code they pulled specifically points to the gas cap, I think the issue is self evident. You could always go buy a new gass cap and see if the problem goes away. If it does, I would have the dealership reimburse you for the cost of the cap.

ash_cpe

Last time with CEL, code showed something going on with fuel pressure and they checked the gas cap, did a "pressure test" and found no issues. But I am buying a gas cap even if they don't replace it this time.

mleskovar

There's a "sticky" for technical bulletins at the beginning of this forum. I seem to remember one about a leak at a plastic coupler from the fill tube to the tank? Maybe your VIN is affected.

BlackBensy

Its crazy how modern cars of today will throw a CEL light just because the cap is not on all the way.

I remember the days of having to really trouble shoot a problem.

Shifter

Really?.. Come on man, cars now are far more complicated and if you think the computer just tells you what's wrong then you have no clue as to what you are taking about.

mleskovar

I remember days when the most complicated piece of 'electronics' in the car was the points capacitor Yea, OBDII is pretty cool when you think about it.

BlackBensy

Obviously you didn't comprehend what I meant.

I was referring to someone mentioning a gas cap can throw a CEL light.

ash_cpe

Thank you all. I got the car from the dealer and they replaced the purge valve as well as updating software, so far so good.