P0140
DTC P0140 HO2S CIRCUIT NO ACTIVITY DETECTED (BANK 1/SENSOR 2)Component Location:
GENERAL DESCRIPTION
The rear heated oxygen sensor is mounted on the rear side of the Catalytic Converter (warm-up catalytic converter) or in the rear exhaust pipe, which is able to detect catalyst efficiency. The rear heated oxygen sensor (HO2S) produces a voltage between 0 V and 1 V. This rear heated oxygen sensor is used to estimate the oxygen Storage capability. If a catalyst has good conversion properties, the oxygen fluctuations are smoothed by the oxygen storage capacity of the catalyst. If the conversion provided by the catalyst is low due to aging, poisoning or misfiring, then the oxygen fluctuations are similar to signals from the front oxygen sensor.
DTC DESCRIPTION
Due to possible oxygen sensor defects (e.g. reference air poisoning) or faults in the injection system (e.g. leaking fuel injector), the rear oxygen sensor may not provide the expected lean or rich signal level during fuel cut-off or full load condition. Hence, the oxygen sensor signal is checked for plausibility during this engine operating states. There are 2 cases which DTC P0140 sets.
1. Signal monitoring during fuel cut-off: The ECM monitors rear ) O2 sensor signal level during fuel cut-off which normally shows near 0 V and sets DTC P0140 when signal level is too high.
2. Signal monitoring after fuel cut-off: The ECM monitors rear O2 sensor signal level after leaving fuel cut-off and sets DTC P0140 when signal remains at or below 0.6 V.
DTC Detecting Condition:
Schematic Diagram:
Signal Waveform And Data Part 1:
Signal Waveform And Data Part 2:
MONITOR DTC STATUS
NOTE: If any DTCs relating to HO2S are stored, do ALL REPAIRS associated with those codes before proceeding with further troubleshooting
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:
- History (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 loose or poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure
YES - Go to next step as below
TERMINAL AND CONNECTOR INSPECTION
1. Ignition "ON" & Engine "OFF".
2. Monitor the O2 SNSR V0L.- B1/S2 parameter on the Scantool data list while wiggling the wiring harness and related connectors. Refer to "Signal Waveform & Data" in the "General Information" procedure.
3. The value should remain more or less unchanged. If not, check for the following conditions:
- Check for corrosion on terminals
- Check for terminal tension (at the HO2S and at the ECM)
- Check for damaged wiring
- Check the HO2S ground circuit for a good connection
- Check the 15 A sensor 2 fuse
- Check front and rear HO2S for connections being reversed.
4. Was a problem found in any of the above areas?
YES - Repair as necessary and go to "Verification of Vehicle Repair" procedure
NO - Go to next step as below
COMPONENT INSPECTION
1. Visually/physically inspect the following conditions:
- Ensure that the sensor is securely installed
- Check for corrosion on terminal
- Check for damaged wiring Repair as necessary and go to next step
2. Warm up the engine to normal operating temperature and let it idle.
3. Connect Scantool and monitor the O2 SNSR V0L.-B1/S2 parameter on the Scantool data list.
Specification :Above 0.6 V at idle
4. Is sensor data near the specified value?
YES - 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 - 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.