DTC P0140 [LF, L3]


id0102008053a3

DTC P0140

Rear HO2S circuit no activity detected

DETECTION CONDITION

• The PCM monitors the input voltage from the rear HO2S when the following conditions are met. If the input voltage from the sensor never exceeds 0.55 V for 30.4 s, the PCM determines that sensor circuit is not activated.
MONITORING CONDITIONS
- HO2S, HO2S heater and TWC repair verification drive mode
- The following conditions are met:
• Engine speed is above 1,500 rpm.
• Engine coolant temperature is above 80 °C {158 °F}.
Diagnostic support note
• This is a continuous monitor (CCM).
• The MIL illuminates if the PCM detects the above malfunction condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.
• The PENDING CODE is available if the PCM detects the above malfunction condition during first drive cycle.
• The FREEZE FRAME DATA is available.
• The DTC is stored in the PCM memory.

POSSIBLE CAUSE

• Rear HO2S deterioration
• Rear HO2S heater malfunction
• Leakage exhaust system
• Open or short to ground circuit between rear HO2S terminal A and PCM terminal 1Y
• Insufficient compression
• Engine malfunction

Diagnostic procedure

STEP

INSPECTION

ACTION

1
PERFORM DTC CONFIRMATION PROCEDURE
• Perform the DTC CONFIRMATION PROCEDURE.
• Is the same DTC present?
Yes
Go to the next step.
No
Intermittent concern exists. Go to the INTERMITTENT CONCERN TROUBLESHOOTING procedure.
2
VERIFY RELATED PENDING AND STORED DTCS
Note
• If the fuel monitor DTC, DTC P0131,or P0132 is retrieved, ignore it until P0140 is fixed.
• Turn the ignition switch to the OFF, then ON (Engine off).
• Verify pending and stored DTCs using the WDS or equivalent.
• Are other DTCs present?
Yes
Go to the appropriate DTC troubleshooting procedures.
No
Go to the next step.
3
IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA
• Is DTC P0140 displayed in the FREEZE FRAME DATA?
Yes
Go to the next step.
No
Go to the troubleshooting procedures for DTC on FREEZE FRAME DATA.
4
VERIFY CURRENT INPUT SIGNAL STATUS
• Warm up the engine.
• Access the O2S12 for P0140 or O2S22 for P0160 PID using the WDS or equivalent.
• Verify the PID while racing the engine at least 10 times (in NEUTRAL (MTX) or PARK (ATX)).
• Is the PID reading normal?
- More than 0.55 V at least once during engine racing.
Yes
Go to step 7.
No
Go to the next step.
5
INSPECT INSTALLATION OF REAR HO2S
• Check if the rear HO2S is loosely installed.
• Is the sensor installed securely?
Yes
Go to the next step.
No
Install the sensor securely, then go to Step 9.
6
INSPECT GAS LEAKAGE FROM EXHAUST SYSTEM
• Visually check if any gas leakage is found between the exhaust pipe and the rear HO2S.
• Is there gas leakage?
Yes
Repair or replace any malfunctioning exhaust parts, then go to Step 9.
No
• Inspect the following wiring harnesses for an open or short to ground circuit, Repair or replace the wiring harness if necessary.
- Rear HO2S terminal A (harness-side) to the PCM terminal 1Y (harness-side)
• Repair or replace the wiring harness if necessary.
• If all items above are normal, replace the malfunctioning sensor.
then go to Step 9.
7
INSPECT SEALING OF ENGINE COOLANT PASSAGE
Warning
• Removing the radiator cap when the radiator is hot is dangerous. Scalding coolant and steam may shoot out and cause serious injury.
• When removing the radiator cap, wrap a thick cloth around and turn it slowly.
• Remove the radiator cap.
• Implement the procedure to bleed air from the engine coolant, then run the engine at idle.
• Are there any small bubbles that makes the engine coolant white at the filling opening?
Note
• Large bubbles are normal since they are remaining air coming out from the engine coolant passage.
Yes
Air penetrates due to from poor sealing of head gasket or other areas between combustion chamber and the engine coolant passage.
Repair or replace malfunctioning parts, then go to Step 9.
No
Go to the next step.
8
INSPECT ENGINE COMPRESSION
• Inspect the engine compression.
• Is it normal?
Yes
Go to the next step.
No
Implement the engine overhaul for repairs, then go to the next step.
9
VERIFY TROUBLESHOOTING OF DTC P0140 COMPLETED
• Make sure to reconnect all disconnected connectors.
• Turn the ignition switch to the ON position (Engine off).
• Clear the DTC from memory using the WDS or equivalent.
• Perform the KOER self-test.
• Is the same DTC present?
Yes
Replace the PCM, then go to the next step.
No
Go to the next step.
10
VERIFY AFTER REPAIR PROCEDURE
• Perform the "After Repair Procedure".
• Are any DTCs present?
Yes
Go to the applicable DTC troubleshooting.
No
Troubleshooting completed.