BMW E46 Fault Codes P-1188, P1189, P0170, P-0173, M52TU, M54
I have a 1999 BMW 323i and the scan code kept coming up p1188/1189 and p0170 and p0173 . What are these codes and how do I correct the the problem?
The P1188 and P1189 codes are for “fuel control” for both banks 1 and 2 (cylinders 1-2 and 4-6, respectively). The P0170 an P0173 are for “fuel trim”, again, for both banks 1 and 2.
With these codes, I would first look for vacuum leaks in the intake system. Inspect the rubber boots going from the MAF (Mass Air Flow sensor) to the throttle body, especially the small leg that connects to the idle control valve, down by the throttle body. Additionally, inspect all vacuum and air handling hoses. Another common vacuum leak source is the crankcase ventilation system. See the link below for additional info on the crankcase ventilation system.
If you cannot find any obvious vacuum leaks, you can have the system “smoke tested”. This injects a smoke into the intake and any leaks will allow the smoke to come out.