DTC P0139

DTC P0139	HO2S circuit slow response
DETECTION CONDITION	The PCM monitors the HO2S inversion cycle period and rich-to-lean response time while under the open loop fuel control (fuel cut off control). If the average response time is more than the specification, the PCM determines that the HO2S circuit response is slow. 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 if 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	Looseness of HO2S Leakage exhaust gas HO2S malfunction Fuel line pressure malfunction Leakage fuel Fuel pump unit malfunction Pressure regulator (built-in fuel pump unit) malfunction AIR system malfunction TP sensor malfunction Eccentric shaft position sensor malfunction Leakage engine coolant Purge solenoid valve malfunction PCM malfunction

HO2S circuit slow response

DETECTION CONDITION

The PCM monitors the HO2S inversion cycle period and rich-to-lean response time while under the open loop fuel control (fuel cut off control). If the average response time is more than the specification, the PCM determines that the HO2S circuit response is slow.

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 if 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

Looseness of HO2S
Leakage exhaust gas
HO2S malfunction
Fuel line pressure malfunction
- Leakage fuel
- Fuel pump unit malfunction
- Pressure regulator (built-in fuel pump unit) malfunction
AIR system malfunction
TP sensor malfunction
Eccentric shaft position sensor malfunction
Leakage engine coolant
Purge solenoid valve malfunction
PCM malfunction

DIAGNOSTIC PROCEDURE

STEP	INSPECTION		ACTION
1	IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA (MODE 2) Is the DTC P0139 on FREEZE FRAME DATA (Mode 2)?	Yes	Go to the next step.
1		No	Go to the troubleshooting procedure for DTC on FREEZE FRAME DATA (Mode 2). (See DTC TABLE ).
2	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.
2		No	Record the FREEZE FRAME DATA (Mode 12) and DIAGNOSTIC MONITORING TEST RESULTS on the repair order, then go to the next step.
3	VERIFY RELATED REPAIR INFORMATION AVAILABILITY Verify related Service Bulletins and/or on-line repair information availability. Is any related repair information available?	Yes	Perform repair or diagnosis according to the available repair information. If the vehicle is not repaired, go to the next step.
3		No	Go to the next step.
4	VERIFY RELATED PENDING CODE OR STORED DTC Turn the ignition switch off, then to the ON position (engine off). Verify the related PENDING CODE or stored DTCs. Is the DTC P0443 also present?	Yes	Go to the DTC P0443 inspection. (See DTC P0443 ).
4		No	Go to the next step.
5	INSPECT INSTALLATION OF HO2S 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. (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION ).
6	INSPECT GAS LEAKAGE FROM EXHAUST SYSTEM Visually inspect if there is any gas leakage between the exhaust manifold and HO2S. Is there gas leakage?	Yes	Repair or replace any malfunctioning exhaust part, then go to Step 15.
6		No	Go to the next step.
7	INSPECT HO2S Inspect the HO2S. (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 FUEL LINE PRESSURE Turn the ignition switch off. Inspect the fuel line pressure while the engine running. (See FUEL LINE PRESSURE INSPECTION ). Is the fuel line pressure normal?	Yes	Go to Step 10.
8		No	Go to the next step.
9	INSPECT FUEL SYSTEM FOR FUEL LEAKAGE Visually inspect fuel leakage in the fuel system. Is there fuel leakage?	Yes	Repair or replace the malfunctioning part according to the inspection results, then go to Step 15.
9		No	Replace the fuel pump unit, then go to Step 15. (See FUEL PUMP UNIT REMOVAL/INSTALLATION ).
10	INSPECT AIR SYSTEM OPERATION Perform the Secondary Air Injection (AIR) System Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION ). Is there any malfunction?	Yes	Repair or replace the malfunctioning part according to the inspection results, then go to Step 15.
10		No	Go to the next step.
11	INSPECT TP SENSOR Inspect the TP sensor. (See THROTTLE POSITION (TP) SENSOR INSPECTION ). Is there any malfunction?	Yes	Replace the throttle body, then go to Step 15. (See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION ).
11		No	Go to the next step.
12	INSPECT ECCENTRIC SHAFT POSITION SENSOR Inspect the eccentric shaft position sensor. (See ECCENTRIC SHAFT POSITION SENSOR INSPECTION ). Is there any malfunction?	Yes	Replace the eccentric shaft position sensor, then go to Step 15. (See ECCENTRIC SHAFT POSITION SENSOR REMOVAL/INSTALLATION ).
12		No	Go to the next step.
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 PURGE SOLENOID VALVE Inspect the purge solenoid valve. (See PURGE SOLENOID VALVE INSPECTION ). Is there any malfunction?	Yes	Replace the purge solenoid valve, then go to the next step.
14		No	Go to the next step.
15	VERIFY TROUBLESHOOTING OF DTC P0139 COMPLETED Make sure to reconnect all disconnected connectors. Clear the DTC from the PCM memory using the M-MDS or equivalent. (See AFTER REPAIR PROCEDURE ). Perform the DRIVE MODE 3 (A/F sensor heater, HO2S heater, A/F sensor, HO2S, and TWC Repair Verification Drive Mode). (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.