For a complete wiring diagram Refer to Section 8W.When Monitored:O2 Sensor Heater Temperature is greater than 496°C (925°F) and battery voltage greater than 10.99 volts.Set Condition:The Oxygen Sensor voltage is stuck rich for a calibrated amount of time. One Trip Fault. Three good trips to turn off the MIL.Possible Causes(K141) O2 1/2 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE(K904) O2 RETURN DOWNSTREAM CIRCUIT SHORTED TO BATTERY VOLTAGE(K141) O2 1/2 SIGNAL CIRCUIT OPEN(K904) O2 RETURN DOWNSTREAM CIRCUIT OPENO2 SENSORPCMAlways perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).1. O2 SENSOR ABOVE 3.7 VOLTSWhen only one O2 Sensor is shorted to voltage, the scan tool will display all O2 Sensor voltage readings at approximately 5.0 volts. When diagnosing this DTC, only diagnose the O2 Sensor that set the DTC.Start the engine.Allow the engine to reach normal operating temperature.With a scan tool, read the 1/2 O2 Sensor voltage.Is the voltage above 3.7 volts?YesGo To 2NoRefer to the INTERMITTENT CONDITION Diagnostic Procedure.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)2. (K141) O2 1/2 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE

Start the engine and allow the engine to idle.Disconnect the 1/2 O2 Sensor harness connector.Measure the voltage on the (K141) O2 1/2 Signal circuit in the O2 Sensor harness connector.Measure the voltage in reference to ground, not the (K904) O2 Return Downstream circuit.Is the voltage above 0 volts?YesRepair the short to battery voltage in the (K141) O2 1/2 Signal circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoGo To 33. (K904) O2 RETURN DOWNSTREAM CIRCUIT SHORTED TO BATTERY VOLTAGE

Turn the ignition off.Disconnect the C2 PCM harness connector.Ignition on, engine not running.Measure the voltage on the (K904) O2 Return Downstream circuit in the O2 Sensor harness connector.Is there any voltage present?YesRepair the short to battery voltage in the (K904) O2 Return Downstream circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoGo To 44. O2 SENSOR

Turn the ignition off.Connect the C2 PCM harness connector.Connect a jumper wire between the (K141) O2 1/2 Signal circuit and the (K904) O2 Return Downstream circuit in the 1/2 O2 Sensor harness connector.Ignition on, engine not running.With a scan tool, monitor the 1/2 O2 Sensor voltage.Is the voltage between 2.3 and 2.7 volts with the jumper wire installed?YesReplace the O2 Sensor.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoGo To 5Remove the jumper wire before continuing.5. (K141) O2 1/2 SIGNAL CIRCUIT OPEN

Turn the ignition off.Disconnect the C1 and C2 PCM harness connectors.Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.Measure the resistance of the (K141) O2 1/2 Signal circuit from the O2 Sensor harness connector to the appropriate terminal of special tool #8815.Is the resistance below 5.0 ohms?YesGo To 6NoRepair the open in the (K141) O2 1/2 Signal circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)6. (K904) O2 RETURN DOWNSTREAM CIRCUIT OPEN

Measure the resistance of the (K904) O2 Return Downstream circuit from the O2 Sensor harness connector to the appropriate terminal of special tool #8815.Is the resistance below 5.0 ohms?YesGo To 7NoRepair the open in the (K904) O2 Return Downstream circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) 7. PCMBefore continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.Were there any problems found?YesRepair as necessary.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoReplace and program the Powertrain Control Module per Service Information.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)