Fuel Cap and SES [Archive] - GrandAmGT.com Forum


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03-28-2008, 09:41 AM
Why is it that if the fuel cap is not tighten the SES light comes on? It has been happening recently with my 2000 grand am se. I will turn the cap until it clicks when I fill up and about 1/4 of a tank the SES light comes on. I fill up tighten cap and it goes off about 4-5 days later.

Any suggestions? Thanks

Lab Rat
03-28-2008, 10:55 AM
New cap?

03-28-2008, 11:07 AM
new cap. It causes a vacuum leak i believe.

03-28-2008, 11:08 AM
Check the gasket on your cap and check the area on the fill tube that the gasket sits on. It has to seal or you get the light. It might be dirt.

If the cap has a bad gasket, get a new one like lab rat suggested.

03-28-2008, 12:32 PM
A new cap should solve that...My brother-in-law has an 04 and he had the same problem went and bought a new cap and its fixed

03-28-2008, 01:38 PM
Yep yep, new cap all the way - mine would do it too. I cleaned up the area around the cap, got a new one and problem is gone!

03-28-2008, 08:16 PM
i have had the same problem since last fall... i replaced the cap and the code will still pop up randomly. it sometimes throws the code 2 times in one day and sometimes once every 2 weeks.

03-30-2008, 12:05 AM
Figure out the code, diagnose the problem. This will happen if you fill up with the engine running as well... big no, no.

The codes have to do with the EVAP system. There is a pressure sensor in your fuel tank. When the pressure from fumes builds, it is released during cruise by the purge solenoid and sucked out of the gas tank and into the engine by natural engine vacuum. The computer does checks and if pressure doesn't build or go down at certain times, then a part of the system is deemed malfunctioning and a code is set.