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Greg A
Greg A , Master Troubleshooter
Category: Chevy
Satisfied Customers: 7819
Experience:  Working with Electronics & Cars for 25+ Years
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2003 Pontiac Sunfire: check engine light..fault code..Replaced gas cap

Resolved Question:

2003 Pontiac Sunfire-check engine light is on and the fault code relates to the evac system. Replaced gas cap and the light is still on.
Submitted: 8 years ago.
Category: Chevy
Expert:  Greg A replied 8 years ago.

HiCustomer Thank you for asking your question on Just Answer.

Did you get a specific error code that you can pass on to us (letter and numbers)?


Customer: replied 8 years ago.
Reply to Greg A's Post: Autozone did the check and I do not have the code
Expert:  Greg A replied 8 years ago.

Hi again.

Did they clear the code, and now it has come back?

If so, is it possible that you could run down there again and have them read the code and write it down?


Customer: replied 8 years ago.
Reply to Greg A's Post: They would not reset because of a $10,000 fine if the problem was not fixed. This problem occurred about year ago and a new gas cap fixed the problem. My son installed a locking gas cap several months ago and the check engine came on about a month ago and then went off after he made sure the gas cap was tight. It came on again this week and I installed the new GM gas cap installed previously and the car has been used numerous times but the light stays on this time. From the GM manual, I know it can be a plugged canister or maybe one of two solenoid switches. The GM manual lists three codes for this problem P0440,P0442 & PP0446. Unfortunately, the car is with my son who lives out of town. The car will be back in several weeks because I do the all the service on the vehicle. Any ideas where to look first based on your experience.
Expert:  Greg A replied 8 years ago.

Hi again. Sorry about the delay.

I was asking about the "clearing of the codes" because it generally takes at least 3 times of the diagnostic tests to be run and pass before the check engine light will be turned off by the cars computer. There will be a history code stored for about 40 cycles (before that one goes away). That is the first time I have heard about a $10K fine. Maybe that is just for the parts places. Most service department procedures have to clear the code as part of the procedure so we can see if the problem HAS been fixed.

Here are the generic descriptions of the codes you mentioned, and a couple more from many GM cars. Not all of these apply to your Sunfire (I only found the three you mentioned in my Sunfire list). Since you have the GM manual for the car, I won't go into the details of each one.

P0440 Evaporative Emission (EVAP) System
P0442 Evaporative Emission (EVAP) System Small Leak Detected
P0443 Evaporative Emission (EVAP) Purge Solenoid Control Circuit
P0446 Evaporative Emission (EVAP) Vent System Performance
P0449 Evaporative Emission (EVAP) Vent Solenoid Control Circuit

And here is a routing diagram of the system hoses and components.


I have found that the "small leak" failures usually trace back to loose or damaged hoses, while "performance" failures usually trace back to one of the solenoids. But this is a very generalized trend. Each system has to be examined, and sometimes given "the smoke test" where a "smoke machine" and pressurized air is used to find the leak. Otherwise it is guessing. Solenoids get damaged more in areas where there is a lot of salt and chemicals used on the roads. I have even found wires pulled loose after someone has driven through the woods!

Please feel no pressure to accept this answer unless it helps you. Please let me know if you have more questions.

Take Care, Greg A.

Greg A, Master Troubleshooter
Category: Chevy
Satisfied Customers: 7819
Experience: Working with Electronics & Cars for 25+ Years
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