DTC P0140

DTC P0140	HO2S no activity detected
DETECTION CONDITION	The PCM monitors the input voltage from the HO2S when the following conditions are met Under the following monitoring conditions, if the input voltage from the HO2S does not even exceed 0.55 V though the short term fuel trim is controlled up to 20.5% for 9.6 s , the PCM determines that sensor circuit is not activated. MONITORING CONDITIONS PCM Adaptive Memory Production, EGR System, A/F Sensor Heater, HO2S Heater, A/F Sensor, HO2S, and TWC Repair Verification Drive Mode Diagnostic support note This is an intermittent monitor (A/F sensor, HO2S). 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. PENDING CODE is available H the PCM detects the above malfunction condition during the first drive cycle. FREEZE FRAME DATA (Mode 2/Mode 12) is available. The DTC is stored in the PCM memory.
POSSIBLE CAUSE	HO2S looseness HO2S connector or terminals malfunction HO2S heater malfunction Short to ground in wiring harness between HO2S terminal A and PCM terminal 2Q PCM connector or terminals malfunction Open circuit in wiring harness between HO2S terminal A and PCM terminal 2Q HO2S malfunction Leakage exhaust system HO2S deterioration Engine malfunction Leakage engine coolant to combustion chamber Insufficient compression PCM malfunction

DIAGNOSTIC PROCEDURE

STEP	INSPECTION		ACTION
1	VERIFY FREEZE FRAME DATA (MODE 12) AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED Have the FREEZE FRAME DATA (Mode 12) and DIAGNOSTIC MONITORING TEST RESULTS (A/F sensor, HO2S related) been recorded?	Yes	Go to the next step.
1		No	Record the FREEZE FRAME DATA (Mode 12) and DIAGNOSTIC MONITORING TEST RESULTS on the repair order, then go to the next step.
2	VERIFY RELATED SERVICE BULLETINS AVAILABILITY Verify related Service Bulletins availability. Is any related Service Bulletins available?	Yes	Perform the repair or diagnosis according to the available Service Bulletins. If the vehicle is not repaired, go to the next step.
2		No	Go to the next step.
3	VERIFY RELATED PENDING AND STORED DTC Note NOTE: If fuel monitor DTC, DTC P0132 is retrieved, ignore it until P0140 is fixed. Turn the ignition switch off, then to the ON position (Engine off). Verify the PENDING CODE and stored DTC using the M-MDS. Are any DTCs present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE ).
3		No	Go to the next step.
4	IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA (MODE 2) Is the DTC P0140 on FREEZE FRAME DATA (Mode 2)?	Yes	Go to the next step.
4		No	Go to the troubleshooting procedures for DTC on FREEZE FRAME DATA (Mode 2). (See DTC TABLE ).
5	INSPECT INSTALLATION OF HO2S Turn the ignition switch off. Inspect if the HO2S is loosely installed. Is the HO2S installed securely?	Yes	Go to the next step.
5		No	Retighten the HO2S, then go to Step 15.
6	INSPECT HO2S CONNECTOR AND TERMINALS Disconnect the HO2S connector. Inspect for poor connection (such as damaged/pulled-out pins, and corrosion). Is there any malfunction?	Yes	Repair or replace the connector or terminals, then go to Step 15.
6		No	Go to the next step.
7	INSPECT HO2S HEATER Inspect the HO2S heater. (See HEATED OXYGEN SENSOR (HO2S) INSPECTION ). Is there any malfunction?	Yes	Replace the HO2S, then go to Step 15. (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION ).
7		No	Go to the next step.
8	INSPECT HO2S SIGNAL CIRCUIT FOR SHORT TO GROUND HO2S connector is disconnected. Inspect for continuity between HO2S terminal A (wiring harness-side) and body ground. Is there continuity?	Yes	If the short to ground circuit could be detected: Repair or replace the wiring harness for a possible short to ground. If the short to ground circuit could not be detected: Replace the PCM (short to ground in PCM internal circuit). (See PCM REMOVAL/INSTALLATION ). Go to Step 15.
8		No	Go to the next step.
9	INSPECT PCM CONNECTOR AND TERMINALS Disconnect the PCM connector. Inspect for poor connection (such as damaged/pulled-out pins, and corrosion). Is there any malfunction?	Yes	Repair or replace the connector or terminals, then go to Step 15.
9		No	Go to the next step.
10	INSPECT HO2S SIGNAL CIRCUIT FOR OPEN CIRCUIT HO2S and PCM connectors are disconnected. Inspect for continuity between PCM terminal 2Q (wiring harness-side) and HO2S terminal A (wiring harness-side). Is there continuity?	Yes	Go to the next step.
10		No	Repair or replace the wiring harness for a possible open circuit, then go to Step 15.
11	INSPECT HO2S Reconnect HO2S and PCM connectors. Inspect the HO2S. (See HEATED OXYGEN SENSOR (HO2S) INSPECTION ). Is there any malfunction?	Yes	Go to the next step.
11		No	Go to Step 13.
12	INSPECT GAS LEAKAGE FROM EXHAUST SYSTEM Visually check if any gas leakage is found between exhaust pipe and HO2S. Is there gas leakage?	Yes	Repair or replace any malfunctioning exhaust part, then go to Step 15.
12		No	Replace the HO2S, then go to Step 15. (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION ).
13	INSPECT SEALING OF ENGINE COOLANT PASSAGE Perform the "ENGINE COOLANT LEAKAGE INSPECTION". (See ENGINE COOLANT LEAKAGE INSPECTION ). Is there any malfunction?	Yes	Repair or replace the malfunctioning part according to the inspection results, then go to Step 15.
13		No	Go to the next step.
14	INSPECT ENGINE COMPRESSION Inspect the engine compression. (See COMPRESSION INSPECTION ). Is there any malfunction?	Yes	Perform the engine overhaul, then go to the next step.
14		No	Go to the next step.
15	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 memory using the M-MDS. Perform the KOER self test (using M-MDS) or Drive Mode 03 (PCM Adaptive Memory Production, EGR System, A/F Sensor Heater, HO2S Heater, A/F Sensor, HO2S, and TWC Repair Verification Drive Mode) (not using M-MDS). (See KOEO/KOER SELF TEST ). (See OBD-II DRIVE MODE ). Is the PENDING CODE for this DTC present?	Yes	Replace the PCM, then go to the next step. (See PCM REMOVAL/INSTALLATION ).
15		No	Go to the next step.
16	VERIFY AFTER REPAIR PROCEDURE Perform the "AFTER REPAIR PROCEDURE". (See AFTER REPAIR PROCEDURE ). Are any DTCs present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE ).
16		No	DTC troubleshooting completed.