z4- P0174 and P0171 errors - system to lean..help a lil'

V

van_gocea

New member
my Z4 2004 - 2.5 i has to error codes that i'm not very sure what i must change the lambda probe or something else ...here are the codes
P0174 - Powertrain ( system to lean - bank 2) -
P0171 - Powertrain (system to lean - bank 1)

Does somebody know something ? :fuelfire:
 
It will most likely be a sensor at fault. I had a P error code stored which was the CPS.

If you type in 'P1074 error code Z4' into Google or P1071 there will be lots of results. That's how I found out about the CPS on mine.
 
Since you have both codes it could be one of the following

MAF Sensor failed
Vacuum leak after the maf (check intake pipe)

Or more rarely since the codes are for both banks the primary lambda probes (in the cat)

Do you find that the revs on startup fluctuate before settling?
 
It will be a split in the rubber biggish Air intake tube between the air filter and the Manifold.
They cost about £28 and its easy to fit yourself.
 
Had these codes on my 2004 3 litre, no difference seen when driving, reset codes and after 70 miles EML back on again, had CCV and pipework replaced on specialist recommendation. 70 miles later EML back on, all air induction pipes ok. Changed MAF and all has been well since. Seems to be codes that are regularly thrown and list of possible faults is quite long if you search this and other BMW forums.
 
van_gocea said:
my Z4 2004 - 2.5 i has to error codes that i'm not very sure what i must change the lambda probe or something else ...here are the codes
P0174 - Powertrain ( system to lean - bank 2) -
P0171 - Powertrain (system to lean - bank 1)

Does somebody know something ? :fuelfire:
Click to expand...
I too had these exact same codes, turned out to be the air intake bypass, smaller concertina like hose which tees onto the main manifold. It was quite difficult to spot as the split was on the narrower diameter section of the hose. £21 and 1/2 hour with the screwdrivers and job done :thumbsup:
 
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