DTC P0140 [L3]


DTC P0140	Rear HO2S circuit no activity detected
DETECTION CONDITION	• The PCM monitors input voltage from the rear HO2S when the following conditions are met. If input voltage from sensor does not exceed 0.55 V for 30 s period, the PCM determines that sensor circuit is not activated. MONITORING CONDITIONS - HO2S, HO2S heater and TWC repair verification drive mode - 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). • MIL illuminates if 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. • PENDING CODE is available if PCM detects the above malfunction condition during first drive cycle. • FREEZE FRAME DATA is available. • 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


STEP	INSPECTION		ACTION
1	PERFORM DTC CONFIRMATION PROCEDURE • Perform DTC CONFIRMATION PROCEDURE. (See DTC CONFIRMATION PROCEDURE [L3].) • Is same DTC present?	Yes	Go to the next step.
1		No	Intermittent concern exists. Go to INTERMITTENT CONCERN TROUBLESHOOTING procedure. (See INTERMITTENT CONCERN TROUBLESHOOTING [L3].)
2	VERIFY RELATED PENDING AND STORED DTCS Note • If fuel monitor DTC, DTC P0131or P0132 is retrieved, ignore it until P0140 is fixed. • Turn the ignition switch off, then to the ON position (Engine off). • Verify pending and stored DTCs using WDS or equivalent. • Is any other DTC present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE [L3].)
2		No	Go to the next step.
3	IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA • Is DTC P0140 on FREEZE FRAME DATA?	Yes	Go to the next step.
3		No	Go to troubleshooting procedures for DTC on FREEZE FRAME DATA. (See DTC TABLE [L3].)
4	VERIFY CURRENT INPUT SIGNAL STATUS • Warm up the engine. • Access O2S12 for P0140 or O2S22 for P0160 PID using WDS or equivalent. • Verify PID while racing the engine at least 10 times (in NEUTRAL). • Is PID reading normal? - More than 0.55 V at least once during the engine racing.	Yes	Go to step 7.
4		No	Go to the next step.
5	INSPECT INSTALLATION OF REAR HO2S • Inspect if the rear HO2S is loosely installed. • Is the sensor installed securely?	Yes	Go to the next step.
5		No	Install the sensor securely, then go to Step 9.
6	INSPECT GAS LEAKAGE FROM EXHAUST SYSTEM • Visually inspect if any gas leakage is found between exhaust pipe and rear HO2S. • Is there any gas leakage?	Yes	Repair or replace the malfunctioning exhaust parts, then go to Step 9.
6		No	• Inspect the following wiring harnesses for open or short to ground circuit, repair or replace the wiring harness if necessary. - Rear HO2S terminal A (wiring harness-side) to PCM terminal 1Y (wiring harness-side) • Repair or replace the wiring harness if necessary. • If all items above are normal, replace the sensor. Then go to Step 9.
7	INSPECT SEALING OF ENGINE COOLANT PASSAGE Warning • Removing radiator cap when radiator is hot is dangerous. Scalding coolant and steam may shoot out and cause serious injury. • When removing radiator cap, wrap a thick cloth around and turn it slowly. • Remove the radiator cap. • Implement procedure to bleed air from engine coolant, then run engine at idle. • Are there any small bubbles, which makes engine coolant white at filler opening? Note • Large bubbles are normal since they are due to remaining air being released from engine coolant passage.	Yes	Air gets in due to poor sealing of head gasket or other areas between combustion chamber and engine coolant passage. Repair or replace the malfunctioning parts, then go to Step 9.
7		No	Go to the next step.
8	INSPECT ENGINE COMPRESSION • Inspect engine compression. (See COMPRESSION INSPECTION [L3].) • Is compression normal?	Yes	Go to the next step.
8		No	Implement 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 the PCM memory using the WDS or equivalent. • Perform KOER self-test. (See KOEO/KOER SELF-TEST PROCEDURE [L3].) • Is the PENDING CODE of same DTC present?	Yes	Replace the PCM, then go to the next step. (See PCM REMOVAL/INSTALLATION [L3].)
9		No	Go to the next step.
10	VERIFY AFTER REPAIR PROCEDURE • Perform "After Repair Procedure". (See AFTER REPAIR PROCEDURE [L3].) • Is there any DTC present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE [L3].)
10		No	Troubleshooting completed.