P0137

P0137-O2 SENSOR 1/2 CIRCUIT LOW







- When Monitored:
With the engine running, battery voltage greater than 10.4 volts, and no O2 sensor heater DTCs present.

- Set Condition:
The Powertrain Control Module (PCM) detects that the 1/2 Oxygen Sensor signal voltage is below approximately 1.5 volts for 2.8 seconds after engine startup. The DTC will set as Pending after one trip and Active after two trips. Three good trips to turn off the MIL.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. DTC IS ACTIVE
1. Turn the ignition on.
2. With a scan tool, select View DTCs. Record DTC and Freeze Frame information.
3. Start the engine and allow it to idle for at least 60 seconds.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.

4. With a scan tool, select View DTCs.

Is the DTC Active at this time?

Yes

- Go To 2

No

- Perform the CHECKING FOR AN INTERMITTENT DTC diagnostic procedure. Checking for an Intermittent DTC.

2. (K141) O2 1/2 SIGNAL CIRCUIT
1. Turn the ignition off.
2. Disconnect the 1/2 Oxygen Sensor harness connector.
3. Turn the ignition on.
4. With a scan tool, read the 1/2 Oxygen Sensor voltage.

Is the 1/2 Oxygen Sensor voltage above 4.8 volts?

Yes

- Go To 3

No

- Go To 5

3. 1/2 OXYGEN SENSOR




1. Measure the voltage on the (K904) O2 Return (Down) circuit in the 1/2 Oxygen Sensor harness connector.

Is the voltage at 2.5 volts?

Yes

- Verify that there is good pin to terminal contact in the O2 Sensor and Powertrain Control Module connectors. If OK, replace the 1/2 O2 Sensor.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.

No

- Go To 4

4. (K904) O2 RETURN (DOWN) CIRCUIT SHORTED TO GROUND




1. Turn the ignition off.
2. Disconnect the C1 Powertrain Control Module (PCM) harness connector.
3. Measure the resistance between ground and the (K904) O2 Return (Down) circuit in the 1/2 Oxygen Sensor harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the (K904) O2 Return (Down) circuit for a short to ground.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.

No

- Go To 5

5. (K141) O2 1/2 SIGNAL CIRCUIT SHORTED TO GROUND




1. Measure the resistance between ground and the (K141) O2 1/2 Signal circuit in the 1/2 Oxygen Sensor harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the (K141) O2 1/2 Signal circuit for a short to ground.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.

No

- Go To 6

6. (K141) O2 1/2 SIGNAL CIRCUIT SHORTED TO THE (K904) O2 RETURN (DOWN) CIRCUIT




1. Measure the resistance between the (K141) O2 1/2 Signal circuit and the (K904) O2 Return (Down) circuit in the 1/2 Oxygen Sensor harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the short between the (K141) O2 1/2 Signal circuit and the (K904) O2 Return (Down) circuit.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.

No

- Go To 7

7. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the 1/2 Oxygen Sensor and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Verify that there is good pin to terminal contact in the 1/2 O2 Sensor and Powertrain Control Module connectors.
5. Perform any Technical Service Bulletins that may apply.

Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.

No

- Replace and program the Powertrain Control Module (PCM).
- Perform the PCM VERIFICATION TEST. PCM Verification Test.