I've read the threads above and am trying to find the least expensive fix for the same fault code. I recently had my oil changed at my local dealership (Santa Clara, Ca.). Everything was fine and drove it home very satisfied. About 2 weeks later the Service Engine light came on and stayed on for a few days. Then is shut off for a 3 days and then came back on. A coworker who repairs cars on the side (but not MINIs) said he could connect his laptop to my car and find out the trouble code.

The code was P0456 and it read, "Evaporative emission system leak detected." We took a look at the o-ring/gasket on the fuel cap and noticed it was cracked. He suggested that might be the problem. But now I'm reading (in these forums) about charcoal canisters. Anyone help a starving writer/account manager with some suggestions? Please help! Thank you!!

 

Charcoal canister is not a typical problem of the 06, replace the gas cap...the problem is that sometimes even once you have fixed the problem until you clear the fault codes from memory the check engine light will stay on. If the gas cap does not fix it the I would take to a dealer and pay the $100.00 diagnostics so that you arent throwing parts on the car. The gas cap is going to be the most common problem.

 

If the gas cap does not resolve the issue, then your best bet (to save time and money)is to have a smoke test performed by a local mechanic. Another common part to fail is the "fuel tank vent valve" (indicated by the yellow dot in pictures below). It's a small device located to the left of the intercooler and is an easy replacement. Although the cost for the part is around $100. I had to replace both the charcoal canister and the leak diagnosis pump.

Since you are looking in that area, there is also one more common issue. The evap scavenge line coming from the rear of the car to the front engine bay (left side of motor above intake and left of intercooler) connecting to an extension that runs under the intercooler. Hard to explain, but the evap line has a slight rubber bulge (connection) where the scavenge line connects to the extension. Where the extension makes a 90˙ turn under the intercooler, the vacuum line rubs against a wire loom harness. This rubbing will eventually wear through the line and create a vacuum leak (see last photo. Simple fix, $10 part and take measure to keep from future rubbing.

 

Thanks cooperking, the new gas cap seems to have done the trick. After dropping over $1,700 in mid-May only to have the Service Engine light come on, was a little frustrating. I figured I might have another $1,000 problem on my hands. Keeping my fingers crossed over the next few weeks.

 

madmike007, I'm going to keep these pictures on file in case I fault code pops up again. I really appreciate these hi-def images. Thanks!

 

Just FYI but that last picture is of the Fuel tank vent valve and NOT the leak Diagnosis Pump. The LDP is on the Charcoal canister at the rear of the vehicle. It actually is typical for a defective Fuel tank vent valve to cause a P0456 fault. The vent valve sticks intermittently causing a small leak when the DMTL pump runs (causing the minor leak detection). So another piece to check out is that fuel tank vent valve.

 

healey67

You are correct! I incorrectly labeled the image and will update. Sorry for the confusion.

 

Glad it seems to be working.....keep us updated!

 

will that fuel tank vent valve have smoke coming from it when you perform a smoke test? I did a smoke test on my car and found huge amounts coming from the dust filter thats located under the right rear wheel well cover. I didn't even think to pop the hood to look there. Another question is: does this car (06 cooper s) have to have the evap system in a closed mode to run a smoke test? I hope this makes sense

 

I should have mentioned that I did rpl. my gas cap and the light came back on after 3 days with the same code. I proceded to drive it another 600 miles (I was on vacation) and the light never went off. I figured it was the same code, that's why I continued on my trip. Once home I recked codes, and the same P0456 was there.

 

that filter in the wheel arch will leak smoke. pull the fuel tank vent valve off and try to blow through it...... if you can its bad.

 

Thanks healey67. i did as you sugested and was NOT able to blow thru it. I also inspected the lines that hooch504 mentioned and those appear good. I might add that once I clear my code it will stay gone for about 3-4 days (that's about 60 miles for me).

 

Well, I just replaced the fuel vent valve a week ago, and so far all is good. I think I finally found my problem. Keeping fingers crossed that the light doesn't come on again

 

Bumping an old thread... After resolving the root cause, Will the light ever turn off on its own or is a reset required by the dealer? If so, can advance auto also perform the reset?
Thanks!