DTC P0140 - Rear Oxygen Sensor Activity Not Detected: Condition

DTC is set when rear oxygen sensor signal voltage does not exceed .45 volts after engine is started, or stays below .45 volts for 19 seconds after engine has reached normal operating temperature. Closed throttle position switch must be off, engine speed at 1500 RPM or greater and voltage supplied to sensor heater. Possible causes are:

• Low fuel level.
• Rear oxygen sensor.
• Open or short circuit between terminal 3D on Engine Control Module (ECM) and terminal "A" (Red/Blue wire) on rear oxygen sensor.
• Open circuit between Engine Control Module (ECM) terminal 3O and terminal "B" (Black/Blue wire) on rear oxygen sensor.
• Intake air system, fuel system and/or ignition system malfunction.