P2237

P2237

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 ECM monitors this signal and determines whether the air/fuel mixture is rich or lean. The ECM 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 ECM monitors front HO2S tip temperature and signal at the same time to check open circuit of Pumping Current Circuit (ECM PIN No. 44). The ECM sets DTC P2237 if front O2 tip temperature is higher than the predetermined threshold and front HO2S signal stuck is detected.
If the same error code is set in the next driving cycle, the ECM illuminates the MIL.

DTC Detecting Condition:

Schematic Diagram:

Signal Waveform:

Monitor DTC Status

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

1. Connect scan tool and select "Diagnostic Trouble Codes (DTCs)" mode
2. Press F5 (INFO) 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"?

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

YES
a. 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
a. Go to next step as below

Pumping Current Circuit Inspection
1. Ignition "OFF"
2. Disconnect HO2S and ECM connectors.
3. Measure resistance between terminals 4 of the sensor harness connector and 44 of the PCM harness connector

Specification : Approx. 0 ohm






4. Is resistance within the specification?

YES
a. Go to "Terminal and Connector Inspection" procedure

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

NO
a. 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
a. 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

NO
a. 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 F5 (INFO) and confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted enable conditions
3. Read "DTC Status" parameter
4. Is parameter displayed "History (Not Present) fault"?

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

NO
a. Go to the applicable troubleshooting procedure.