Gas cap warning light problem
 

Hi, recent purchaser of a pre-owned '07 X5 3.0i about six weeks ago, and new to these forums. I've been happy with the car, but I've had one problem so far, the gas cap warning keeps coming on and triggering the check engine light.

First time was after my first fillup, so possibly user error that I didn't tighten it enough. I had to bring it to the dealer service dept to get it cleared.

But later on, about 300 miles into another tank, the gas cap warning diagram in red would flash for a second or two and disappear, then it flashed again and triggered the check engine light again. The light has stayed on for the past 200 miles. I don't think it was user error this time as it was fine for 300 miles.

1. Will the check engine light clear itself eventually? Or do I always have to take it to the dealer?
2. Is there potentially a faulty cap, filler tube, that is the cause and would need to be replaced? I am at 49,000 miles, so want to have them check for any repair parts before the original warranty expires.
3. Could it be likely caused by temporary factors - water in gas, low-grade gas, cold temps, or coming down from high altitude (was in Lake Tahoe the previous week)?

There is an emissions valve in the filler neck that could be the problem. I had that on a 1 month old '08 550i.

If it is just a loose gas cap, and it is tightened, it can clear itself. If something else is causing it, obviously that needs to be repaired first.

Reading the codes may indicate what component is causing the problem.

It can be a faulty cap that isn't sealing.
It can be a leak in the evaporative emissions control system
It can be a fault in the air pump that creates pressure in the fuel tank and evaporative emissions control system
It can be a sensor in that system.

It is not caused by your gasoline or driving down from higher altitude.

Get the dealer to look at it and read the codes while you are under warranty. Your emissions system warranty may have a different term than your full vehicle warranty though.

Perfect advice on the possible causes, and what it is NOT.

Recognize that if the code "clears itself" it will just turn off the light, but the code remains stored until the memory is reset.

Do not allow this to go past 50k miles. It is NOT covered by the emissions warranty as I recall- only a few specified parts are covered by the 7/70 or 8/80 emissions warranty...and dealers will charge you for labor to diagnose too.

Thanks for the comments. I do have a OBD reader that shows the error code is P0442 Evaporative System Small Leak, which seems to be the one caused by loose gas cap, but also if there's a faulty seal or leak.

I do have the CPO warranty after I pass 50K miles, do you know if these parts and repair might be covered under the CPO warranty (less $50 deductible)?

^^If I had a CPO warranty on my car, I'd also have a copy of the actual CPO warranty statement..and I'd read it, and find out if it is covered!

A new gas cap is under $50.... but why not just bring it to the dealer under warranty????

I am bringing it to the dealer under original warranty. I'm just trying to assess what will happen if they just clear the code, and the code pops up again a month later when I'm out of the original warranty.

Also having purchased both third-party auto warranties before, and gotten this CPO warranty (didn't pay for it, it was being offered as a promotional incentive by all dealers), it can be exceedingly unclear what is covered, so seeking anyone with previous firsthand knowledge.

Engine is covered, fuel system is covered, electrical is covered. Emissions is not mentioned, so is it not covered, or covered under something else? And is the evaporative system in the fuel tank considered part of emissions or fuel system? Is a faulty sensor part of emissions or electical? A gas cap is $50 but replacing the filler tube is probably $500, fuel tank $2000...

As long as you have written documentation the problem existed and was addressed by the dealer before the warranty ran out, BMW, and other companies, will typically cover any subsequent repair for the same issue, shortly out of warranty.

If the documentation is not specific... you have a harder case.

I had a leak on one of the power steering hoses. I had oil everywhere. I took off hose, replaced and refilled with new fluid. The service engine light soon light came on. I drove it to work this afternoon, 39 miles each way. Came back to town, filled up gas tank. Ensured the cap was tight. light still on. What do you think the odds of the light and the power steering being changed are related? Will light go out soon, maybe?

Maybe, but could the oil that sprayed everywhere have impacted any of the emission control systems? If so, it isn't likely to go out on its own. Get the codes read so you know what the problem is.