check gas cap light

[liam821]

My old 2004 PY M3 decided it missed me. The "check gas cap" light came on for the new owner literally on the way home from leaving my house. He messed with it for a bit and wasn't able to get it fixed. He was leaving on a three-week trip, so I offered to have a look while he was gone.

Pulled the codes, DME reports:

180 - Tank leak detected
181 - Fuel filler cap open/missing

Things that I've checked/changed:

New BMW Fuel Tank Breather Valve 13901433603 (under the intake manifold)
New gas cap (a known working one AND a new one)
Leak detection pump 16137193479 (connects to the charcoal canister next to the exhaust)
There was a small crack in the filler vent hose (don't think it was leaking, though), which attaches to the fuel filler, so I replaced the whole thing
Checked all the wiring, normal resistance in the fuel tank breather valve
No gas smell anywhere
I've smoked tested the whole system - no leaks.

Gas cap light won't go away.

Thoughts?

[///Marecki]

I recently got one because I was in a rush and drove away from the pump with the tank open (embarrassing). Needless to say, after I closed it up again the light persisted for a bit until I drove some.

So, perhaps you've already fixed it with one of your small fixes like the new cap and its just not being reflected on the cluster because you haven't driven around a bit?

[liam821]

Took it on a 20 minute trip to the store and another 20 minutes back home, around 20 miles round trip. Figure that is plenty long enough, light stayed on.

This happened to me a few years ago (same car), the fuel tank breather valve died. I replaced it with a cheapo Amazon unit since at the time I wasn't sure what was wrong. It fixed the problem, and I never replaced the valve. When the light came on this time around, first thing I did was buy a OEM BMW part figuring the cheapo Amazon part just died, sadly it didn't fix the problem.

[///Marecki]

That's a bummer, I was being hopeful for you.

[maw1124]

Don't these reset with number of startup sequences not miles driven? I'm no expert and I'm sure there's some number of miles at which they reset but I doubt 20 is enough. I'd expect it to be gone in regulars use over the three weeks. Maybe unlock and start it daily without driving it to not rack up miles.

maw

[sapote]

Gas cap light won't go away.

Thoughts?

Did you clear the code using obd reader or inpa?
Last time the fuel tank breather valve died on our 325i and I cleared the code and replaced the valve, and code has not come back.

[liam821]

Did you clear the code using obd reader or inpa?
Last time the fuel tank breather valve died on our 325i and I cleared the code and replaced the valve, and code has not come back.

No, I haven't manually cleared the codes. The car is due for DEQ (smog testing), and if I clear the codes, I'd have to go through the whole readiness checks again. So I'm hoping to avoid that.