Monitored & Set Conditions

1/1 Heated Oxygen Sensor (HO2S) heater operation is monitored after ignition is turned off and engine cools down. DTC will be stored in Powertrain Control Module (PCM) if no upstream oxygen sensor signal is received when PCM powers up oxygen sensor heater. Possible causes are: intermittent condition, defective 1/1 HO2S, defective Auto Shutdown (ASD) relay circuit, or defective connectors or wiring.