P2271

DTC P2271 O2 SENSOR SIGNAL STUCK RICH (BANK 1 / SENSOR 2)

Component Location:

GENERAL DESCRIPTION
In the catalytic process, CO, H2, and HC are oxidized to form CO2 and H2O, while the constituents of NOx are reduced to N2 and O2. A three-way catalytic converter and a closed-loop control system are essential elements in achieving adequate reductions in all three pollutants. The heated oxygen sensor on the back of the Catalytic Converter (warm-up catalytic converter) detects the aging of the converter.

DTC DESCRIPTION
The ECM tests rear O2 sensor signal level during the time the lambda target point is being shifted to lean to determine rear O2 sensor signal stuck. The ECM sets DTC P2271 if rear O2 sensor signal is above the predetermined threshold while target lambda point is being shifted to the predetermined value. If the same error code is set in the next driving cycle, the ECM illuminates the MIL.

DTC Detecting Condition:

Schematic Diagram:

Signal Waveform And Data Part 1:

Signal Waveform And Data Part 2:

MONITOR DTC STATUS
1. Connect scan tool and select "Diagnostic Trouble Codes (DTCs)" mode.
2. Press F4 (DTAL) to select DTC information from the DTCs menu.
3. Confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions.
4. Read "DTC Status" parameter.
5. Is parameter displayed "History (Not Present) fault"?

NOTE:
- (Not Present) fault: DTC occurred but has been cleared.
- Present fault: DTC is occurring at present time.

YES - Fault is intermittent caused by poor contact in the sensor's and/or ECM's connector or was repaired and ECM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.

NO - Go to next step as below.

COMPONENT INSPECTION

HO2S INSPECTION
1. Visually/physically inspect the HO2S for the following conditions:
- Ensure that the HO2S is securely installed. (Pigtail and wiring harness not making contact with the exhaust pipe)
- Check for corrosion on terminals and terminal tension (at the HO2S and at the ECM)
- Front HO2S for silicon contamination. This contamination will be indicated by a white powdery coating on the portion of the sensor exposed to the exhaust stream and this will result in a but false (high) voltage signal
- Fuel, engine coolant or oil contamination
- Use of improper sealant
- If contamination is evident on the HO2S, Fix the source of the sensor contamination before replacing the sensor to prevent future contamination. Go to "Verification of Vehicle Repair" procedure.

2. Warm up the engine to normal operating temperature and let it idle.
3. Connect Scantool and monitor the "O2 SNSR VOL.-B1/S1" and "O2 SNSR VOL.-B1/S2" parameters on the Scantool data list.

Specification : Refer to "Signal Waveform & Data" in the "General Information" procedure

- Front HO2S (O2 SNSR VOL.-B1/S1) : Approx. 1.5 - 2.0 V with idle after warm up
Sensor voltage decrease during engine acceleration and increase during engine deceleration Approx. 3.0 - 4.0 V when fuel cut
- Rear HO2S (O2 SNSR VOL.-B1/S2) : Above 0.7 V at idle

4. Was a problem found in any of the above areas?

YES - Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.

NO - Check for poor connection between ECM and component: backed out terminal, improper mating, broken locks or poor terminal to wire connection. Repair as necessary and go to "Verification of Vehicle Repair" procedure.

VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Connect scan tool and select "Diagnostic Trouble Codes (DTCs)" mode.
2. Press F4 (DTAL) and confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions.
3. Read "DTC Status" parameter.
4. Is parameter displayed "History (Not Present) fault"?

YES - System performing to specification at this time. Clear the DTC

NO - Go to the applicable troubleshooting procedure.