Codes 2774 & 321C. Any advise welcome

[DarkFlameMS]

Hello,

I am looking for advise on a particular engine code combo which I discovered after not being able to pass smog. At the certification place I got a report with the dreaded P0442. I later checked the codes again at home with Bimmerlink and got codes 2774 and 321C.

2774: Air mass, plausibility: air mass too high
321C: Tank deration and purging air system, fine leak: leakage greater than 1.0 mm

I have only owned this vehicle for a couple of weeks and the first time I drove it I got the "TIGHTEN FUEL CAP" message on the dashboard. After looking into it I noticed it didn't have a gas tank cap so I ordered one from ebay and installed it once it arrived.

Then a week after when trying to register the car, failing smog and reading about the codes I immediately thought of the missing gas cap and was sure code 321C would go away after a drive cycle but the next day the code came back. I then proceeded to buy yet another gas cap from O'Reillys hoping the one I got from ebay was not good and a new one would solve my issue.

I haven't been able to do another drive cycle yet but I think I am missing a piece of the puzzle by focusing on the gas cap and not paying attention to code 2774.

I am not very knowledgeable so I appreciate any advise you can give me on this code combo. Tutorials I've seen on similar issues all seem to rely on using a smoke machine to try to detect a leak but as I said I am not sure if I might have a leak or both my issues are linked to the gas cap. What do you think?

2013 BMW X5
Engine N55
89K miles

[Mido01]

Any updates?

[garrypeterson]

I'd start by looking at the evap purge valve. If stuck open it could cause both of those codes.

2774 = air entering the intake without going through MAF (vacuum leak)
321C = EVAP test detected leak