DTC P0146 - HO2S INSUFFICIENT ACTIVITY BANK 1, SENSOR 3 GMC Envoy I

Note. For circuit reference, see WIRING DIAGRAMS - 4.3L article.

Circuit Description

VCM provides about 0.45 volt reference to Heated Oxygen Sensor (HO2S). HO2S sensor signal voltage varies from about one volt when exhaust is rich to about 0.1 volt when exhaust is lean. VCM reads and stores sensor voltage information and evaluates the voltage samples to determine amount of time sensor voltage is out of range. If HO2S voltage is out of predetermined range, DTC will set.

Conditions for setting DTC

1. No ECT, EVAP, IAT, MAF, MAP or TP sensor DTCs set.
2. No other DTC tests in progress.
3. No device controls active.
4. System voltage at least 9 volts.
5. Engine run time greater than 2 minutes.
6. HO2S voltage is greater than .299 volts, but less than .598 volts.