P0137

P0137-O2 SENSOR 1/2 CIRCUIT LOW





For a complete wiring diagram Refer to the Wiring Information.

- When Monitored:
Engine running for less than 30 seconds and the O2 Sensor Heater Temperature is less than 251° C (484° F) with battery voltage greater 10.99 volts.

- Set Condition:
The PCM detects that the 1/2 Oxygen Sensor signal voltage is below approximately 1.5 volts for 2.8 seconds after engine start-up. 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. ACTIVE DTC
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

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. . Intermittent Condition Test

2. (K141) O2 1/2 SIGNAL CIRCUIT
1. Turn the ignition off.
2. Disconnect the 1/2 O2 Sensor harness connector.
3. Ignition on, engine not running.
4. With a scan tool, monitor the 1/2 O2 Sensor voltage.

Is the O2 Sensor voltage between 4.1 and 5.0 volts?

Yes

- Go To 3

No

- Go To 5

3. O2 SENSOR




1. Measure the voltage on the (K904) O2 Return Downstream circuit in the O2 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 POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 4

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




1. Turn the ignition off.
2. Disconnect the C2 PCM harness connector.
3. Measure the resistance between ground and the (K904) O2 Return Downstream circuit in the O2 Sensor harness connector.

Is the resistance below 100 ohms?

Yes

- Repair the short to ground in the (K904) O2 Return Downstream circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 8

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




1. Turn the ignition off.
2. Disconnect the C1 and C2 PCM harness connectors.
3. Measure the resistance between ground and the (K141) O2 1/2 Signal circuit in the O2 Sensor harness connector.

Is the resistance below 100 ohms?

Yes

- Repair the short to ground in the (K141) O2 1/2 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 6

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




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

Is the resistance below 100 ohms?

Yes

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

No

- Go To 7

7. (K141) O2 1/2 SIGNAL CIRCUIT SHORTED TO THE (Z933) O2 1/2 HEATER GROUND CIRCUIT




1. Measure the resistance between the (K141) O2 1/2 Signal circuit and the (Z933) O2 1/2 Heater ground circuit in the O2 Sensor harness connector.

Is the resistance below 100 ohms?

Yes

- Repair the short between the (Z933) O2 1/2 Heater ground circuit and the (K141) O2 1/2 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 8

8. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Oxygen Sensor 1/2 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. Verify that there is good pin to terminal contact in the 1/2 O2 Sensor and Powertrain Control Module connectors.
4. Search for any Technical Service Bulletins that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace and program the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.