Hello. I have a 2016 F55 (S), picked up CPO after my 2014 F55 self immolated. :-(

A few days after the CPO warranty expired, it threw a P0440. I performed a simple inspection of the gas cap and cleaned the ring and seat. I've done some searching and not finding much online about diagnosing the P0440.

Would someone please point me to some guidance on resolving this?

Thank you

 

I've had this one before.
It may be the gas cap and if it is then tighten it and it should go away in a few cycles.

If not, then likely it's the fuel tank breather valve, part no. 13907621174. Very easy DIY replacement and you could probably find the discounted OEM part somewhere on eBay like I did if you don't want to shell out $110.

DIY involves just pulling a clip and it is located right in front of the engine.

Let me know if you have any questions!

 

Thank you. This has been going on for a bit, after both a fill up or two, opening and closing the cap, etc. The code went away for a couple days and then came back, so I'll look at replacing the valve. Thanks!

 

Do you remember if the fault cleared up instantly after installation or if it takes a few cycles? As you can imagine, I installed the new valve, turned on the car and took it around the block and the fault was still there. But that's only one cycle.

Thanks

 

If I recall correctly, it took a few cycles before it went away, but it did not stay for more than a day. I recommend seeing if it goes away after going through a full tank of gas before looking into it further. Does the car seem any different with the code on?

 

Thank you. Fault is gone. I'm hopeful it stays that way! No, car didn't seem different at all, fault or not.

 

Great, that's what I love to hear! Generally, those valves go bad after topping off at the pump regularly. I'm glad it seemed to have fixed the issue for you, knock on wood.