DTC P0139: 1/2 O2 Sensor Slow Response: Description

1/2 Heated Oxygen Sensor (HO2S) voltage is monitored with engine running at idle. DTC will be set in Powertrain Control Module (PCM) memory when PCM senses that 1/2 HO2S voltage is switching from less than 0.39 volt to more than 0.58 volt and back less times than required. Possible causes for DTC to set are: exhaust leak, defective 1/2 HO2S, or defective connectors or wiring.