P0174 - Bank 2 too lean

[Jeespinozar]

Hello guys,

I hope you can help me. I got this error code (P0174) and the dealer replaced the MAF sensor and reset the error code.
The error came back and now they are quoting me 1600 to replace the crankcase cover.

Suddenly, in 2013,i have replaced:

Error code that I did not bother to check with my ODB2 reader
- HPFP - Only thing free
- Low pressure fuel pump
- Gas sensor
- Gas control module
- Gas tank exhaust or vent, something like that

New error P0174
- MAF

Any idea, what the problem would be?

From the last invoice, I could see that the dealer performed a CO2 test and vacuum test, the replacement of the MAF cleared the error, but after couple of days came back.

Thanks for your help

[Dackelone]

So you paid a dealer for a repair and that did not fix the problem. ? Why not talk the service manager about that! Or call BMW NA ?


IF your gonna try to fix it yourself or have another shop look at it... I would buy a can of CRC non-flammable BrakeKleen. Make sure you use NON-Flammable brake kleen!!! With the engine running I would spray it around your valve cover. You might need to remove the fake valve cover(four 6mm hex allens) to reveal the spark plug coil packs and the real plastic valve cover underneath the fake cover.

Most common thing would be a leaking oil fill cap. Take a good look at the rubber gasket for it. Maybe try another cap. Do you have any oil leaks? I would think IF your valve cover is leaking at idle(any whistling noises?) when you get some boost your VC would leak too. So look for oil leaks.

Also... the vacuum lines for the Waste Gate actuators tend to pop off. They are to the left of the valve cover as you are looking at the engine from the front of the car.

Did you dealer ever do a smoke test?

Good Luck,
Dackel

[Jeespinozar]

Hello Dackel,
Thanks for your comment.
Let me copy what the dealer report says:

...performed smoke test on intake system and turbocharger control system. No substantial leak found, after several minutes of pressure a very small amount of smoke can be seen near the connection of the right lower intercooler.
Performed cranckcase ventilation system test and found a reading of 1.0116, when checking a similar new car found it to be 1.0172, which is the BMW spec.
The crankcase vacuum in this vehicle is too low which could cause the excessive oil consumption and mixture adaptation faults...

[Dackelone]

You know another thought is charge pipe. Many guys have had that crack on them. You could pull it off and inspect it. Although a vacuum leak would be from BEHIND the throttle valve(you have a N54 right? bc N55's don't have a throttle plate) until the head. Anywhere between those two places... if you had a vacuum leak... it would be there. And of course via any vacuum line plumbing/hoses covers, etc. I think it might be time to get your hands a little dirty!

[Jeespinozar]

I was thinking the same, I will take the charge pipe out this weekend and check it out. I would assume that a crack should be small and hopefully noticeable. Yes I do have a N54 135i 2005 with 67K miles
Thanks so much
Let's see what i can find

[Jeespinozar]

I changed PCV, injectors and 2 seals by the intercooler

Originally we changed just the PCV and errors went from P0174 to P0172
Measurement of the lean condition found that the oxygen/fuel ratio was off by 25% on bank 2, causing the error.

After that dealer changed the injectors and the rubber seals by the intercooler (just in case). Car has been fine for more than 6 months now