Check Engine light comes on and off repeatedly

[ichiban]

So I got a check engine light about a month ago, car felt the same, but i kept it under 3k rpm, and made an appointment. The day before I was suppose to go to the dealer the light goes away. So i decides to drop in anyways.

My service writer tells me to leave the car with them and they'll pull the code. When i picked it up, they told me it was a gas tank leak, aka i forgot to close the gas cap. I was very confused, cause i'm pretty sure I got that thing closed up tight. So i go home feeling really retarded.

Fast forward 1 day, the light comes back on, stays on for 1 day, then goes away. And now, after a week, the light comes back on. I'm pretty sure it's just gonna go away in a day or two. What do you guys think it is?

TIA

[BMW-driver]

1) Do you have a tune?
2) It might be just a broken sensor (Lambda), but it can be 1000 other things too Just go to BMW

[ichiban]

nah, no tune. Only a RR exhaust, no DP.

[jeremyc74]

Take it back in. It's a common problem, and they've had to replace a few fuel tanks and other components because of it. It's not something you want to let go on toward the end of the warranty period for sure.

[Robert]

had similar issue, SA said its sticky gas tank valve