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BMW 2008 E60 535I no check engine light, fault code mixture control, I think this code arrived after changing Nitrogen oxide sensor fuel trim when engine is cold bank 1 short term -13 long term -0,8 %. Bank 2 short term -22 long term 6,2. 02 sensor pegged rich but with fast idle and let off throttle pedal 02 sensor goes instantly lean for me I think 02 sensor working. Engine warm fuel trim is ok but 02 sensor still pegged rich.
I will do some more checking tomorrow. By the way all the fault code that pointed to Nitro oxygen sensor did not comeback after new sensor.
Started today's testing by plugging in the scanner and ignition on and looking at IAT sensor and ETC after car sitting over night value was IAT 17C ETC 18C, started the car and long term fuel trim bank 1 -2 short term -18 bank 2 long term 0 short term -22. 02 sensor bank1 and 2 I guess bias voltage both 0,450v. Test drove the car everything is perfect 02 switching and fuel trim around 0 both long term and short term.
02 sensor bank 2 for a short moment pegged rich. After driving the car at idle fuel trim ok. Yesterday one DTC in BMW program 2A2C mixture control 2, after today's test drive it was 2A2C and 29D1 misfire cyl5. Misfire cyl 5 was earlier and the shop changed coil for a new one and has not return before today that was when the car had nitrogen sensor code also. No check engine light or codes in generic mode.
Shorted injector is possible I guess but why getting better when warm up. Other way around would more indicate shorted injector.
Let's see if I do some further testing with Pico
