After replacing the gas cap on a 2004 Malibu Maxx with ac delco locking model gt264 why would your check gas cap light come on?

Answer 1

Reset the computer by disconnecting the negative battery cable for a couple of minutes then reconnect. This will erase the codes from the computer. If everything is okay, the CHECK ENGINE light will stay off. The codes are stored in the computer when there is a problem. Even if you fix the problem, the codes are still there until you reset the computer.

When the key is first turned to ACC an air pump will pump the additional air out of the tank and lines. You can hear it - and so check for the sound first to make sure it is working. This is what this error is about - your loosing pressure in the fuel system. The computer tracks the number of trips and will TURN ITSELF OFF only after you have completed TWO successful trips with the tank pressurized. These are actual trips from what I understand the car has to operate for 15min. You can use an ODB-II reader and clear the codes - but the underlining problem will only throw the code again - so save your money.

- Check your gas cap and replace it if it is not fitting tightly or the gasket looks worn. If you suspect the gasket - get some petroleum jelly and put it around the cap gasket to help it get a good seal. TWO trips remember - it won't work the first time. If you try two trips and this still doesn't work - replace the gas cap for around $25.00 maybe even get a LOCK cap since most GM's don't have a secure gas tank. This is the easiest thing to do - so give it a try. You'll like it;)

- I found that the gas cap light problem occurs during the winter season mostly because of the change in air temp. There is an EVAP system that I understand tries to take water out of the fuel (from condensation I assume). There can be ice build up on the EVAP VALVE. Park the car in a warm spot and let everything warm up. This is a cheap solution - so give it a try. You might like this better!

- There is something called an EVAP VALVE at the end of the EVAP system and this fails or gets stuck frequently on the 3800 engines (Pontiac Grand Prix) (not sure if the EVAP system is considered part of the engine setup. The original dude that answered this post mentioned his Malibu had it on the top of the tank and had a solinoid - I can't imagine GM would use terribly different design for these cars - so have a look in the trunk or under the seat.

- The next option is to get the ODB-II code from the engine itself and see what your in for. There are a number of codes thrown depending on how big the issue is going to be. You can look the code up once you have it. The code will not tell you it is such and such it will only tell you how big the problem could be (large leak v.s. small leak). Mechanics have a diagnostic chart which has them comb over the EVAP system looking for potential issues. I have this chart for the 199- models and it is not terribly far off from my 2005 - the codes are slightly different.

FYI on the Dealership. Never take your car to the dealer they are incompetent. I bought my car from Roy Foss - THE WORST service ever. I later found out that they sold me a car with half the transmission missing. Mechanic said it should never have driven off the lot. Great car crappy dealership network - ROY FOSS - never buy from these people.

This is to share my side about that light Check Gas Cap. I bought it brand new and that light was on when I drove it home. Brought it back the next day and have it re-set. Following day it came on again. Brought it back and have it scheduled for testing. Smoke testing. They replace the gas tank. Brand new and have parts replaced already. Just imagine making new car smell like oil already. Mechanic dirty. After a week from the day of repair the same problem came out, check gas cap. Brought it back and they said crack gas carbon filter whatsoever they call it is crack and need to be replaced. Have to rent car which warranty pay for it but not the sales tax. Lo and behold no more Check Gas Cap light. Take it to test. Loosen gas cap if it works. No lights come on. I notify dealer and they try to explain any way they want to explain. I suspect that Check Gas Cap light was being disabled. I suspect that there was no problem on fuel system but the program or sensor are not working right. I complain to BBB and GM offer me one year of free oil change. I dislike their customer service representative.

Just so you know, there is absolutely no way to disable the check gas cap message on your car. You really think that a dealership, which gets paid to work on your car, is going to break federal law and their franchise agreement just to screw with you?

Reason the light did not come on is that the EVAP self test only runs under certain conditions. And what "program or sensor not working right" would you be referring to?

2/4/2010 - After replacing the gas cap, and the above not clearing the problem, I took my 2005 Malibu maxx (133K miles) to my favorite professional shop...they diagnosed my problem as stuck evaporator solonoid. I was told it is on top of the tank, on the passenger side. Replacement will be about $170.