CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

EVAP and ME

I have a 2002 Checy Suburban with 136,000 miles. I purchased this in April of 2009. The service engine light has come on four times since then and each time it has been to the EVAP system. The dealer I boughy it from has not given me the codes so I cannot say what they were.



The first time it went on was because of a leak somewhere in the EVAP system. It was cleared thinking I had left the car running while fill it up or the cap was not on tight. Teh secong time they blew smoke and found the leak. Third time it was for a faulty valve which was replaced at the dealer, and they cut me a break since thier 30 day warrenty had expired, but it still involved the same system. Fourth time was this morning and the tech said there was just a loose connection.



In the end my questions are 1) Are these systems prone to problems? I’ve never had an engine light or car problem related to this system befoer and 2) Are they that hard to fix that this keeps happening.



Sorry for the length. Just trying to get all the info out there.

I can’t understand why they never told you what codes they were getting. You can get them read for free at Autozone, it’d be helpful to know exactly what they are.

A high percentage of evap codes are gas cap related. It’s possible that a new gas cap may cure this, but please get the codes if you can and post them here.

IMHO we see far too many EVAP system problems on this forum, enough to suggest that yes, EVAP systems in general are prone to problems. And yeah, when they do happen it seems that the ability to fix them is somewhat lacking in the average garage.

And as long as diesel trucks continue to pour out unburned hydrocarbons in unfathomable amounts (along with all the other “nastys” that are considered mortal sin when coming from cars) completely unchecked, then I’ll continue to feel that EVAP systems being required to be virtually perfect are extreme overkill.

Sorry to spout off. But yeah, you have lots of company for somethng that should not be.

They checked the cap the first time I brought it in and excluded that. I believe that is why they smoked the system the second time to figure out where the leak was.

I knew to ask for the codes but I figured that after the problem was fixed the first time that it would not get to the point of posting, so I didn’t ask.

I just got back from vacation and the darned light went on again. I’m betting dollars to doughnuts that it is the EVAP system again. I believe that this time it will be the wiring, either connectors or a short.

Any suggestions on whether I shoudl take this to an auto electrical system specialist or let the dealer try to tackle this again.

I’ll post the codes when I get them this time.

Yes, EVAP problems can be a real bear to nail down. Take a look at the pneumatic and electrical schematics for them and you’ll see why. I chased down an EVAP leak on my 2 year old Camry for some time before finding the real culprit. The gas filler neck had rusted slightly, was lightly pitted and although the gas cap tested good, it failed to seal completely against the neck. Just look at all the interfaces where it can leak and the high standard (IMHO) that it’s held to and it’s no wonder they can be problematic.

This is one system I would go to a dealer for diagnostics if you aren’t equipped to do it yourself. Theoretically, the dealer should be better equipped and have more exposure to fixing these issues on a specific make/model than a “general practitioner”.