P2271

P2271-O2 SENSOR 1/2 SIGNAL STUCK RICH

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





- When Monitored:
No global or monitor conflicts or disabling conditions present. During a decel condition, fuel shut off event after the following conditions have been met: 1. Upstream O2 Sensor in closed loop; 2. Engine run time greater than one minute; 3. Engine coolant temperature above 65°C (149°F); 4. Engine speed above 2016 RPM; 5. Vehicle speed above 88.5 kph (55 mph) 6. Catalyst temperature between 600°C and 800°C (1112°F and 1472°F).

- Set Condition:
The Powertrain Control Module (PCM) detects that the downstream O2 Sensor does not transition from rich to lean. Two trip fault. Three good trips will turn off the MIL.





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

Diagnostic Test

1. DTC IS ACTIVE

NOTE: Diagnose and repair any O2 Sensor or fuel system related DTCs before proceeding with this diagnostic procedure.

1. Start 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 may result in possible serious or fatal injury.

2. Test drive the vehicle according to the monitoring conditions.
3. With a scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

- Go To 2

No

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

2. CHECKING THE EXHAUST SYSTEM FOR LEAKS
1. Turn the ignition off.
2. Perform the CHECKING THE EXHAUST SYSTEM FOR LEAKS diagnostic procedure. Checking The Exhaust System For Leaks.

Were any problems found?

Yes

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

No

- Go To 3

3. CHECK THE FUEL SYSTEM
1. Check the entire fuel system for high fuel pressure, excessive fuel volume, or leaking Fuel Injectors. Testing and Inspection.

Were any problems found?

Yes

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

No

- Go To 4

4. O2 SENSOR
1. Replace the O2 Sensor.
2. Turn the ignition on.
3. With the scan tool, erase DTCs.
4. Start 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 may result in possible serious or fatal injury.

5. Test drive the vehicle according to the monitoring conditions.
6. With a scan tool, select View DTCs.

Did the DTC return?

Yes

- Go To 5

No

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

5. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the 1/2 O2 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. Refer to any Technical Service Bulletins 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. .
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.