Freaking P0171 P0174 codes

[Court X3]

Been running this down for about a month now and need some advice, light came on after getting gas, so first checked the fit to make sure it was snug, no problem.

Then started researching and trying to find easy fixes, so far have done the following:

Checked gas cap, cleared SES light came back one day later
Cleaned Maf, cleared SES light came back one day later
Removed intake boot, checked for cracks none found

waiting on:
Spark plugs
Air Filter (noticed mine had a tear along the edge, but don't think that would trip SES)

If that doesn't fix it, leaning on replacing the MAF

[Roman D]

Yeah, lean fuel mixture bank1 and 2, sounds familiar. Dont forget pcv system that can cause vacuum leaks, o2 sensors themselves(low brobability) and may be Disa valve

[Roman D]

I, actually, did precisely that. new fuel cap, new spark plugs, air filter and fuel filter.. Keep in mind that the fuel filter isn't just a can with two holes and, well, filter.. It, also has a pressure regulator. If it is original one or very old, you may want to have that addressed.
And no, it did not solve the problem
I have PCV valve, OFH gasket, valve cover gasket, two O2 sensors, a used airflow sensor, intake elbow boot (just in case- car passed smoke test so I hope I wont need it) 3 meters of vacuum lines, trottle body seal/gasket all in my garage, hopefully I will get a chance to do all that over the weekend.

[E38flagship]

I had this same problem ended up being the disa valve seal. I bought a replacement seal off eBay as the valve was still good

[E38flagship]

https://m.youtube.com/watch?v=lqYVFIq4NB8

If your valave is faulty you can also get a code for lean mixture

[Court X3]

Thanks going to check that out as well

[cmccrac]

Hey guys, could really use a bump on this thread. Ive got 4 o2 sensor codes showing lean upstream and downstream as well as a code for connection to pcm. Car has been stumbling at times for months before the codes showed up. Also, having intermittent random misfire codes. Could use some advice....is this a bad o2 sensor leaning out banks1 & 2, not communicating with the computer, or good sensors indicating vacuum leak or perhaps poor fuel delivery. Which of the two scenarios is more likely to accompany random misfire? Thanks in advance.

[cmccrac]

Codes are
P 0300
P 0147
P0149
P114D
P2195
P2197

[Court X3]

I'd go with scenario two

[Court X3]

Should have posted remedy, my problem turned out to be DISA valve seal but replaced both O2 sensors while in there.