ok guys i need some help to run self diagnostics on this code i am getting for the evap system.
the car is an 03 cts with 99000 miles on it. I have been getting the check gas cap on the center panel for a while now, and never really had any problems til a few months ago when the code P0440 came up. so i replaced the gas cap with a new one but the code came back. the car runs fine with no noticable problems. it starts everytime when i fuel it up, has power, etc. the only real problem that i can see is that my fuel mileage went from 22 to 15, and when i start it in the morning and let it warm up i can smell gas fumes in the exhaust pipe(because i went back there and put my nose to the pipe)(well not all the way to the pipe but about 6 inches). i have researched this and seen the purge valve, and selonoid, and all that, and the fuel pressure sensor, but the thing i need is to figure out how i can diagnos this problem myself going step by step, so the first step was to hook up the scanner to retrieve and clear codes. then replace gas cap, then visually inspect all lines that i can get to without having to take anything off. so basically i am going from the easiest point first to the hardest point last. If anyone can help me then i will appreciate it
06-13-13, 08:35 PM
Only way to properly diagnose a EVAP system is to have a factory capable scan tool and a EVAP smoker. EVAP leaks can be so small that you won't find it without smoking the system. To have it correctly diagnosed have a reputable shop do it.
06-14-13, 11:40 AM
Re: 2003 CTS P0440 code
that is costly. i am gonna make my own smoke tester, and do that myself. just thought maybe there was a better process of elimination that i can go through with out having to take it ti the dealer, or a shop.
06-14-13, 08:52 PM
Smoke machine uses only baby oil, and without a capable scan tool a smoker is useless. You also needs special tools to remove Schroeder valve and adapters for test port. Not as simple as making a smoke machine and smoking it (and throwing parts at it will cost more than having a shop diagnose it and you replace the parts).