P0161 OBD Trouble Code

O2 Sensor Heater Circuit

HO2S Heater Circuit Conditions

Cold engine startup requirement met (ECT sensor input less than 147°F, BTS ambient air input at ±59°F of ECT input), then the test started and PCM detected that the rear HO2S-22 signal remained over 300 mv for 30-90 seconds

HO2S Heater Circuit Conditions

Engine running for 1 minute, then the PCM detected an open or short in the HO2S heater circuit

HO2S Heater Circuit Conditions

Engine runtime over 2 seconds, system voltage from 11.7-18v, MAF input less than 27 g/sec (less than 35 g/sec on 5.7L engine), ECT and I AT inputs less than 91°F and the difference between ECT and IAT inputs less than 9°F, then the PCM detected that the HO2S-22 signal remained within 150 mv of the startup HO2S-22 signal voltage, conditions met for 130 seconds after a cold startup iVofe Test invalid if system voltage is out-of-range for 4 seconds