Diagnostic Test
- O2 SENSOR BELOW 1.5 VOLTS
- Start the engine.
- Allow the engine to reach normal operating temperature.
- With a scan tool, read the 1/1 O2 Sensor voltage.
Is the voltage below 1.5 volts?
Yes
- Go to step 2
No
- Perform the INTERMITTENT CONDITION diagnostic procedure. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure .
- (K41) O2 SENSOR 1/1 SIGNAL CIRCUIT
- O2 SENSOR
- Measure the voltage on the (K902) O2 Return Upstream circuit in the O2 Sensor harness connector.
Is the voltage at 2.5 volts?
Yes
- Replace the O2 Sensor.
- Perform the POWERTRAIN VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure .
No
- Go to step 4
- Measure the voltage on the (K902) O2 Return Upstream circuit in the O2 Sensor harness connector.
- (K902) O2 RETURN UPSTREAM CIRCUIT SHORTED TO GROUND
- Turn the ignition off.
- Disconnect the PCM harness connectors.
- Measure the resistance between ground and the (K902) O2 Upstream Return circuit in the O2 Sensor harness connector.
Is the resistance below 100 Ohms?
Yes
- Repair the short to ground in the (K902) O2 Return Upstream circuit.
- Perform the POWERTRAIN VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure .
No
- Go to step 8
- (K41) O2 SENSOR 1/1 SIGNAL CIRCUIT SHORTED TO GROUND
- Turn the ignition off.
- Disconnect the PCM harness connectors.
- Measure the resistance between ground and the (K41) O2 Sensor 1/1 Signal circuit in the O2 Sensor harness connector.
Is the resistance below 100 Ohms?
Yes
- Repair the short to ground in the (K41) O2 Sensor 1/1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure .
No
- Go to step 6
- (K41) O2 SENSOR 1/1 SIGNAL CIRCUIT SHORTED TO (K902) O2 RETURN UPSTREAM CIRCUIT
- Measure the resistance between the (K41) O2 Sensor 1/1 Signal circuit and the (K902) O2 Return Upstream circuit in the O2 Sensor harness connector.
Is the resistance below 100 Ohms?
Yes
- Repair the short between the (K902) O2 Return Upstream circuit and the (K41) O2 Sensor 1/1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure .
No
- Go to step 7
- Measure the resistance between the (K41) O2 Sensor 1/1 Signal circuit and the (K902) O2 Return Upstream circuit in the O2 Sensor harness connector.
- (K41) O2 SENSOR 1/1 SIGNAL CIRCUIT SHORTED TO THE (Z902) O2 1/1 HEATER GROUND CIRCUIT
- Measure the resistance between the (K41) O2 Sensor 1/1 Signal circuit and the (Z902) O2 1/1Heater ground circuit in the O2 Sensor harness connector.
Is the resistance below 100 Ohms?
Yes
- Repair the short between the (Z902) O2 1/1 Heater ground circuit and the (K41) O2 Sensor 1/1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure .
No
- Go to step 8
- Measure the resistance between the (K41) O2 Sensor 1/1 Signal circuit and the (Z902) O2 1/1Heater ground circuit in the O2 Sensor harness connector.
- PCM NOTE: Before 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?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure .
No
- Replace and program the Powertrain Control Module in accordance with the Service Information.
- Perform the POWERTRAIN VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure .
- Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.