P2271-O2 SENSOR 1/2 SIGNAL BIASED RICH
For a complete wiring diagram Refer to Section 8W.
- When Monitored:
With the engine running, the odometer greater than the minimum mileage allowable for catalyst break-in, and no global or monitor conflicts or disabling conditions present. The test will only run if the monitor has not already run and passed or failed.
- Set Condition:
The PCM detects that the sensor does not output a voltage greater than a calibrated high voltage value and less than a calibrated low voltage value within a specific time period. If the voltage pass values are not achieved after the total accumulated test time, a pending fault will be set. An active fault is matured on a second trip failure. Three good trips will turn off the MIL.
| Possible Causes |
| INTERMITTENT DTC |
| EXHAUST LEAK |
| OXYGEN SENSOR WIRING OR CONNECTORS |
| O2 SENSOR SIGNAL CIRCUIT |
| O2 SENSOR RETURN CIRCUIT |
| 1/2 OXYGEN SENSOR |
| POWERTRAIN CONTROL MODULE (PCM) |
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).
Diagnostic Test
1. DTC IS ACTIVEStart the engine and allow it to reach 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 can result in personal injury or death.
NOTE: It may be necessary to test drive the vehicle within the DTC monitoring conditions in order for this DTC to set.
With a scan tool, select View DTCs.
Is the status Active for this DTC?
Yes
- Go to 2
No
- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
2. CHECKING THE EXHAUST SYSTEM FOR LEAKS
Perform the diagnostic procedure for *CHECKING THE EXHAUST SYSTEM FOR LEAKS.
Were any problems found?
Yes
- Repair as necessary.
- Perform the PCM Verification Test. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
- Go to 3
3. CHECKING THE OXYGEN SENSOR OPERATION
NOTE: Check for signs of contaminants that may have damaged the O2 Sensor, such as contaminated fuel, unapproved silicone, oil and coolant.
Perform the diagnostic procedure for *CHECKING THE OXYGEN SENSOR OPERATION.
Were any problems found?
Yes
- Repair as necessary.
- Perform the PCM Verification Test. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
- Go to 4
4. POWERTRAIN CONTROL MODULE (PCM)
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).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Refer to any Technical Service Bulletins that may apply.
Were any problems found?
Yes
- Repair as necessary.
- Perform the PCM Verification Test. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
- Replace and program the Powertrain Control Module (PCM) in accordance with the Service Information.
- Perform the PCM Verification Test. (Refer to 9 - ENGINE - STANDARD PROCEDURE)