P2231

DTC P2231 HO2S SIGNAL CIRCUIT SHORTED TO HEATER CIRCUIT (BANK1 SENSOR1)

COMPONENT LOCATION

GENERAL DESCRIPTION
The linear O2 sensor is mounted on the front side of the Catalytic Converter (warm-up catalytic converter) or in the front exhaust pipe. It detects a wide range of air/fuel ratios in the exhaust gas from the rich to lean regions. This linear O2 sensor produces a current that corresponds to a specific air/fuel ratio. The PCM monitors this signal and determines whether the air/fuel mixture is rich or lean. The PCM constantly monitors the linear O2 sensor and increases or decreases the fuel injection duration using this signal. This is called closed-loop fuel control operation.

DTC DESCRIPTION
The PCM compares front HO2S signal with model signal. This comparison will determine loss of insulation resistance between heater circuit and sensor circuit of front HO2S. The PCM sets DTC P2231. if the difference between HO2S. signal and model signal is bigger than the predetermined threshold. If the same error code is set in the next driving cycle, the PCM illuminates the MIL.

Signal Waveform:

MONITOR DTC STATUS

NOTE: If any DTCs relating to HO2S are present, DO ALL REPAIRS associated with those codes before proceeding with this troubleshooting free.

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:
1. History (Not Present) fault: DTC occurred but has been cleared.
2. Present fault: DTC is occurring at present time.

YES: Fault is intermittent caused by poor contact in the sensor's and/or PCM's connector or was repaired and PCM 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.

SHORT TO HEATER CIRCUIT INSPECTION
1. Ignition "OFF"
2. Disconnect HO2S and PCM connectors.
3. Measure resistance between terminals 6 and 1 of the sensor harness connector
4. Measure resistance between terminals 6 and 2 of the sensor harness connector
5. Measure resistance between terminals 6 and 3 of the sensor harness connector





6. Measure resistance between terminals 6 and 4 of the sensor harness connector
Specification: Above 400 kOhm

7. Is resistance within the specification?

YES: Go to "Terminal and Connector Inspection" procedure

NO: Repair as necessary and go to "Verification of Vehicle Repair" procedure

TERMINAL AND CONNECTOR INSPECTION
1. Many malfunctions in the electrical system are caused by poor harness(es) and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage
3. Has a problem been found?

YES: Repair as necessary and go to "Verification of Vehicle Repair" procedure

NO: Go to "Component Inspection" procedure

COMPONENT INSPECTION
1. Visually/physically inspect following items:
- Visually/physically inspect the front HO2S for contamination, deterioration, or damage.
- Inspect the front HO2S for any silicon contamination. This contamination will be indicated by a white powdery Coating and this will result in a but false voltage signal
- If contamination is evident on the HO2S, replace contaminated sensor and go to next step.

2. Warm up the engine to normal operating temperature and check that HO2S signal is active.




3. Connect Scantool and monitor the "O2 SNSR VOLT.(B1/S1)" parameter on the Scantool data list.
Test Condition : Engine "ON" & In Closed loop mode

4. Is sensor data near the specified value?

YES: Check for poor connection between PCM 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

NO: Check HO2S for contamination, deterioration, or damage. Substitute with a known-good HO2S and check for proper operation. If the problem is corrected, replace HO2S and then 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.