12-02-2012, 09:48 AM
Join Date: Mar 2011
Mein Auto: 325i
My PO171 & PO174 Journey
Well, at 150 miles on the trip odometer yesterday my SES light came on... again- same codes as before:
PO171 CNF - Bank 1 System Too Lean
PO174 CNF - Bank 2 System Too Lean
I've been using a couple of threads as a resource as I've tried to track down the problem(s) and in particular this one has been very helpful.
So far I've done the following, all OEM:
Replaced torn intake boot, upper and lower replaced
Replaced MAF sensor
Replaced Fuel filter
Cleaned the DISA & inspected, ordered new gasket
Then I got sidetracked when my car wouldn't start and replaced my failed fuel pump (see following thread)
After I swapped the fuel pump for a new one I reset the SES and at 150 miles it turned back on yesterday. I think my plan is to continue my journey with a CCV replacement. With 120k on the car I'm sure it needs to be done anyway but I'm really hoping that it fixes both my SES light and some low idle problems. The car idles significantly better than when I started this whole process but it still occasionally dips a little low at stoplights.
I think I'm going to order the cold weather CCV from OEMBimmerparts. They sell a kit that comes with appropriate gaskets and the vacuum lines as well as the CCV unit, seems like a good deal...
I'll keep you all posted and if anyone else has any bright ideas for things I should do well I'm in there I'd appreciate the advice!