Check Gas Cap light causing Check Engine light

Maintenance/Repairs
1

I have a ‘check engine’ light on because of an oxygen sensor(check gas cap message is displayed and had it hooked up to find out which codes came up) and have an inspection coming up.

I actually had the gas cap replaced thinking the seal might be faulty after all these years and the message went off…for awhile. I know after having the codes cleared you have to drive 50 or so miles to reset the computer but the cap clearly isn’t giving a good seal to reach that point. Given a new cap is in place, is there a safe way to seal it, if only temproarily?

The vehicle is only driven sparingly(in town, less that ten miles a trip a couple times a week) so I’d like to avoid dropping hundreds for a repair like this if possible.

Does anyone have any suggestions?

2

Apply a coating of petroleum jelly on the gas cap seal.

Tester

1 Like
3

Pay to have it diagnosed

“check gas cap” is simply the pcm telling you that the evap system won’t hold the correct amount of vacuum for the specified time frame

Could be a bad cap, rotten filler hose, fuel tank not sealing properly, bad purge valve, and so forth

It could even be something as serious s the purge valve not having proper power and ground for various reasons

Just what is this mystery vehicle?

1 Like
4

@Tester, I’ll give that a try, thank you.

@db4690 lol I really should have stated that as well since a great deal can differ from car to car; it’s a 2007 Buick Lacerne with 103,000 miles. Runs great except for this little issue.

I’m going to try the petroleum trick today to see if helps.

5

That’s a very nice car :+1:

6

Agree with all the possible causes listed by db4690.

My wife is somehow surprisingly rough on gas filler necks, and I find they get pretty dinged up after a few years so the gas cap has a hard time making a seal.

7

What have you done to correct the oxygen sensor problem?

8

My wife is somehow surprisingly rough on gas filler necks, and I find they get pretty dinged up after a few years so the gas cap has a hard time making a seal.

How do you get your wife to put gas in? When my wife’s car is low on gas she want’me to use so I have to fill it.

9

Is she physically leaning on the nozzle, when she’s at the filling station . . . ?!

I’ve seen a few distorted filler necks, and that’s sometimes been the root cause

2 Likes
10

Response to Renegade: That was easy. One day many years ago, we were driving my wife’s car, and my daughters had been watching some Fast and Furious (or similar) movie. They asked how people spin the back tires while the car sits still. So I showed them. My wife, who was sitting in the passenger seat, turned to me and said “you are never driving my car again!”

3 Likes
11

Unfortunately, after getting the codes today it appears that it’s not just a single code that’s responsible for the ‘check engine’ light so even if the petroleum jelly fixed the seal issue, others will persist. I don’t have the print out in front of me but it looks like a repair bill of some amount is unavoidable.

Even so, I appreciate everyone’s input and who knows, maybe others might read the topic and be helped if they have a similar issue.

12

share with us the codes and perhaps we can help.