Good day Folks,
Thanks for your help Mike.
I have a 2006 Buick Rendezvous, my 2nd Rendezvous 1st was 2002, but this one has a bit of a problem. For the last year the gas cap alarm comes on every so often which logs an error on the computer. I have had the gas tank pressure tested twice, a new sensor installed and even a new gas cap. The alarm keeps coming back. I know I can't be the only one with this problem so I'm looking for any suggestions. I have been taking the vehicle to a dealership but they can't seem to fix the problem. This has become a real concern because it has failed the E-test and without that I can't register the car.
Hope there'* some help out there.
Harry

Did you buy an aftermarket gas cap, or OEM? Have you tried sanding the top lip of the filler neck (where it interfaces to the gas cap) and putting grease or vaseline there to assure a good seal?

Yes it was an OEM cap and I had done all that you have mentioned. I have also sent a request off today to GM asking them to respond. Hopefully they come back with some info as well.

Do you know the exact DTC code your getting? Is there any sort of pattern when the code pops up (ie certain fuel level etc)?

the vent valves like to stick open. could be any leak really but thats the second most common ive come across. the fist is the cap seal but you replaced that. ive had good luck shooting some wd40 in the valve and actuating it a bunch of times and see of that helps. on my 03 monte that lasted 5 times as long as buying a new one from the dealer

The codes that have come up are p0446 and p0445. Even with the new valve it alarmed after about 130 kms.

those are circuit faults so there must be something wrong with the wiring or connectors if you replaced the valve

Thank you for the info. I'll be passing it on to the mechanic. I'm still waiting for a response from GM but they said it would be 24 hours.
Harry

Good day Folks,
I was in error about one of the codes, it was P0455, which is a vacuum leak. The problem was the purge & vent solenoid. When checked, it worked electronically but wasn't working mechanically. My E-mail to GM customer care paid off. It only took about a year and a half to find the problem. But and there'* always a but, GM in their infinite wisdom set the operating parameters for the vacuum monitor to work at 4 to 30 C. This in a vehicle for North America. It still can't get the test passed because of this one monitor. I may have to take a trip down south. Thanks for all your help and suggestions.
Harry

normally you can get the others to go ready with a few longer drives shutting the key off after then start it warm and take another drive. i dont know where you are but in ny we can have one so even of the evap isnt ready if all the others are it will pass