My engine light came on today...

I took it to auto zone to do the free test and here is what the thing said, evap emission control leak large. I drive an 04 cavalier. Anyone familiar with the problem?

DTC P0445. (EVAP Emissions control leak-LARGE)

Yup, I've got the same code and its on my 04 Sunfire. Been dealing with it since December, still haven't figured it out yet. Start checking the plastic hard EVAP lines in the engine bay and back near the gas tank.

I think my issue is gas tank related myself as I have seen a yellowish fluid drippng off my exhaust which should no way in hell be there and only place I can think of it coming from is the tank.

If you cannot figure out the problem yourself, take it to a GM dealership and have them put in a smoke machine and that will find the leak. You pay them their diagnostic fee and fix the issue yourself.



Its not a big deal if you don't fix it right away, so don't worry about it too much. I just hate looking at the damn CEL light after a while.

The EVAP system vent valve is very common on GMs... probably accounts for over half the leaks on them. They have no filter (some have a foam block that really doesn't do anything), so the valve gets stuck partially open. On the '04s, I believe the threshold for "large" leak is only .020" (definately no more than .040"), so it doesn't take much to set this code. The valve is cheap, so if you don't find an obvius leak, it's probably worth it to just replace it. Also, if you havn't already, make sure the gas cap is on tight and that there are noc racks on the sealing ring.

You don't necessarily have to take it to the dealer for a diagnostic smoke check, at around $1,000, many independant shops also have them and almost always charge a lot less for the test.