P0137

P0137-O2 SENSOR 1/2 CIRCUIT LOW







- 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 oxygen sensor signal voltage is below 1.5 volts for 3 seconds after starting engine. One Trip Fault. Three good trips to turn off the MIL.





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

1. O2 SENSOR BELOW 1.5 VOLTS
1. Start the engine.
2. Allow the engine to reach normal operating temperature.
3. With a scan tool, read the 1/2 O2 Sensor voltage.

Is the voltage below 1.5 volts?

Yes

- Go To 2

No

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition Test
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification 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 1/2 O2 Sensor voltage above 4.8 volts?

Yes

- Go To 3

No

- Go To 5

3. O2 SENSOR




1. Measure the voltage on the (K902) O2 Downstream Return circuit in the O2 Sensor harness connector.

Is the voltage at 2.5 volts?

Yes

- Replace the O2 Sensor.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 4

4. (K902) O2 DOWNSTREAM RETURN CIRCUIT SHORTED TO GROUND




1. Turn the ignition off.
2. Disconnect the PCM harness connectors.
3. Measure the resistance between ground and the (K902) O2 Downstream Return circuit in the O2 Sensor harness connector.

Is the resistance below 100 ohms?

Yes

- Repair the short to ground in the (K902) O2 Downstream Return 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 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 (K902) O2 DOWNSTREAM RETURN CIRCUIT




1. Measure the resistance between the (K141) O2 1/2 Signal circuit and the (K902) O2 Downstream Return circuit in the O2 Sensor harness connector.

Is the resistance below 100 ohms?

Yes

- Repair the short between the (K902) O2 Downstream Return 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 (Z902) O2 1/2 HEATER GROUND CIRCUIT




1. Measure the resistance between the (K141) O2 1/2 Signal circuit and the (Z902) O2 1/2 Heater ground circuit in the O2 Sensor harness connector.

Is the resistance below 100 ohms?

Yes

- Repair the short between the (Z902) 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. PCM

NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

1. 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. Powertrain Verification Test

No

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