DTC P0140 [L3]


DTC P0140	Rear HO2S circuit no activity detected
DETECTION CONDITION	• PCM monitors input voltage from rear HO2S when the following conditions are met. If input voltage from sensor does not exceed 0.55 V for 30 s period, 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 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 ignition key to OFF, then ON (Engine OFF). • Verify pending and stored DTCs using WDS or equivalent. • Is any other DTC present?	Yes	Go to appropriate DTC troubleshooting procedures. (See DTC TABLE [L3].)
2		No	Go to next step.
3	IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA • Is DTC P0140 on FREEZE FRAME DATA?	Yes	Go to 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 engine. • Access O2S12 for P0140 or O2S22 for P0160 PID using WDS or equivalent. • Verify PID while racing engine at least 10 times (in NEUTRAL). • Is PID reading okay? - More than 0.55 V at least once during engine racing.	Yes	Go to step 7.
4		No	Go to next step.
5	INSPECT INSTALLATION OF REAR HO2S • Inspect if rear HO2S is loosely installed. • Is sensor installed securely?	Yes	Go to next step.
5		No	Install 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 any faulty exhaust parts, then go to Step 9.
6		No	• Inspect the following harnesses for open or short to ground circuit, repair or replace harness if necessary. - Rear HO2S terminal A (harness-side) to PCM terminal 1Y (harness-side) • Repair or replace harness if necessary. • If all items above are okay, replace faulty 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 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 faulty parts, then go to Step 9.
7		No	Go to next step.
8	INSPECT ENGINE COMPRESSION • Inspect engine compression. (See COMPRESSION INSPECTION [L3].) • Is compression okay?	Yes	Go to next step.
8		No	Implement engine overhaul for repairs, then go to next step.
9	VERIFY TROUBLESHOOTING OF DTC P0140 COMPLETED • Make sure to reconnect all disconnected connectors. • Turn ignition key to ON (Engine OFF). • Clear DTC from memory using WDS or equivalent. • Perform KOER self-test. (See KOEO/KOER SELF-TEST PROCEDURE [L3].) • Is PENDING CODE of same DTC present?	Yes	Replace PCM, then go to next step. (See PCM REMOVAL/INSTALLATION [L3].)
9		No	Go to next step.
10	VERIFY AFTER REPAIR PROCEDURE • Perform "After Repair Procedure". (See AFTER REPAIR PROCEDURE [L3].) • Is there any DTC present?	Yes	Go to applicable DTC troubleshooting. (See DTC TABLE [L3].)
10		No	Troubleshooting completed.