P0131

P0131-O2 SENSOR 1/1 CIRCUIT LOW





For a complete wiring diagram, refer to the Wiring Information.

- When Monitored:
With the engine running for less than 30 seconds, the Oxygen Sensor 1/1 heater temperature less than 251° C (484° F) and the battery voltage greater than 10.4 volts.

- Set Condition:
The Powertrain Control Module (PCM) detects that the Oxygen Sensor 1/1 signal voltage is below 2.5196 volts for 6 seconds after engine startup. 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. OXYGEN SENSOR 1/1 VOLTAGE
1. Start the engine and allow it to reach normal operating temperature.

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.

2. With a scan tool, monitor the 1/1 O2 Sensor Volts.

Is the voltage less than 2.52 volts?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

2. (K41) O2 1/1 SIGNAL CIRCUIT VOLTAGE
1. Turn the ignition off.
2. Disconnect the Oxygen Sensor 1/1 harness connector.
3. Turn the ignition on.
4. With a scan tool, monitor the 1/1 O2 Sensor Volts.

Is the voltage above 4.8 volts?

Yes

- Go To 3

No

- Go To 5

3. OXYGEN SENSOR 1/1




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

Is the voltage between 2.475 and 2.525 volts?

Yes

- Replace the Oxygen Sensor 1/1. Oxygen Sensor - Removal.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 4

4. (K902) O2 1/1 RETURN CIRCUIT SHORTED TO GROUND




1. Turn the ignition off.
2. Disconnect the Powertrain Control Module (PCM) harness connector.
3. Measure the resistance between ground and the (K902) O2 1/1 Return circuit in the Oxygen Sensor 1/1 harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the (K902) O2 1/1 Return circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 8

5. (K41) O2 1/1 SIGNAL CIRCUIT SHORTED TO GROUND




1. Measure the resistance between ground and the (K41) O2 1/1 Signal circuit in the Oxygen Sensor 1/1 harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the (K41) O2 1/1 Signal circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 6

6. (K41) O2 1/1 SIGNAL CIRCUIT SHORTED TO THE (K902) O2 1/1 RETURN CIRCUIT




1. Measure the resistance between the (K41) O2 1/1 Signal circuit and the (K902) O2 1/1 Return circuit in the Oxygen Sensor 1/1 harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the short between the (K902) O2 1/1 Return circuit and the (K41) O2 1/1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 7

7. (K41) O2 1/1 SIGNAL CIRCUIT SHORTED TO THE (Z909) GROUND CIRCUIT




1. Measure the resistance between the (K41) O2 1/1 Signal circuit and the (Z909) Ground circuit in the Oxygen Sensor 1/1 harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the short between the (Z909) Ground circuit and the (K41) O2 1/1 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 1/1 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. Perform any Technical Service Bulletins (TSBs) that may apply.

Were any problems found?

Yes

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

No

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