What is the diagnostic code for O2 sensor circuit slow response?
What is the diagnostic code for O2 sensor circuit slow response? P0139 is a diagnostic trouble code (DTC) for "O2 Sensor Circuit Slow Response (Bank 1, Sensor 2)". Why is Bank 1 O2 sensor so slow? The O2 sensor for bank 1 sensor 2 should be replaced only after all other checks of the fuel and exhaust systems test okay. The slow response of an O2 sensor may be due to a sensor that is just getting old and over time may get contaminated with time with carbon and other contaminants that deteriorate the sensor over time. Which is Bank...