optionray

Previously posted in the z06 forum

Just bought my Z06 with the Z07 suspension (less than 500 miles). I noticed a gas smell in the garage a couple of days ago and realized the check engine light was on. I called on-star and they said I have a P0442 code (evaporative emission system issue). They suggested I give it a few days because it was probably some bad gas or a gas cap issue ( wouldn't that be great if that was the issue?), and fill it up. So, that is what I did, hoping the issue would resolve itself and the check engine light would cycle off in a few days.

I drove the car the next day and noticed a little gas under the car (almost directly behind the driver side, and straight back from the gas opening, after I spelled the gas again. I could actually see the gas dripping, but after a while (about 4 hours), it stopped dripping. I pulled the car into the garage and there was no more gas leak when I checked the following morning. I thought all was well

I took the car out again today and put about 80 miles on it (trying to hit the 500 mile mark), returned and parked the car in the garage and just noticed the smell again. Sure enough, more gas had dripped again in the same place. Although, I think it has stopped dripping now, I'm pretty sure it will not drip anymore tonight.

I will plan on bringing it to the dealer this week but had a question I'd like to ask the more technically oriented, just to put my mind at ease (hopefully).

Is it possible the system is going through some kind of test, putting pressure on the system to check it. And in the process, is pushing some gas out of something that only holds a little bit of gas and might have a leak, or relief valve, or even maybe just needs to be tightened or secured? Or would you suspect a more serious problem requiring major work?

Thanks for any ideas you have?

NSC5

It probably is not major work but it isn't something that is going to self correct. The basic evaporative emission system has been around for a long time and as it name implies it prevents gas vapor from the tank from going into the environment by trapping the fumes in a charcoal canister and when the engine is operating the vapor is extracted from the canister. It does go through a self check but none of that would create fumes and certainly not liquid from a properly operating system.

It is pretty simple if the dealer identifies the failed component (cracked canister, broken check valve, etc.) properly the first time and does it right. It did take the Cadillac dealer 3 attempts to get it right for my 2014 ATS with less than 300 miles on it. Attempt one was replacement of the broken canister and replacement of the plugged (with charcoal debris) valve along with blowing out the hoses in this system. 60 miles later same DTC set and the valve was once again stuck because there was still charcoal in the hose; valve replaced again and hoses "more carefully" cleaned. 100 miles later repeat at which point I told them that was the last chance on a car that still hadn't made it to 500 miles. This time they finally contacted GM tech support and were directed to replace the tubing and valves in the system and the problem has not returned. So the system and problem should be simple but if you have a "simple" tech working on it the fix will take longer than it should.

optionray

^^^ Any idea if they have to drop the tranny, or do you think it is pretty easy getting to these areas? Thanks for your reply.

NSC5

Hopefully it won't be highly invasive but it all depends upon where the actual problem lies. If the fuel tank has to come out there will be significant disassembly. Best not to worry too much until the dealer looks at it because you might ruin the rest of your weekend worrying about a repair that could turn out quite simply.

Good luck and make sure to take it to a dealer that sells a lot of Corvettes. You want a tech who has some experience and understands the lay of the land. I would try to contact a local Corvette club for recommendations about a good servicing dealer.