DTC P2271

DTC P2271	HO2S signal stuck rich
DETECTION CONDITION	The PCM monitors the input voltage from the HO2S when the following conditions are met. If the input voltage is more than 0.85 V for 40 s, the PCM determines that the HO2S signal remains rich. MONITORING CONDITIONS ECT: more than 70°C {158°F} Engine speed: more than 1, 500 rpm MAF amount: more than 10 g/s {1.32 lb/min} Short term fuel trim: -20-20% Long term fuel trim: -50-50% Target A/F feedback system status: feedback control 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	Loose installation of HO2S Leakage exhaust gas HO2S malfunction Fuel line pressure malfunction Fuel pump unit malfunction Pressure regulator (built-in fuel pump unit) malfunction Purge solenoid valve malfunction Fuel injector malfunction Leakage engine coolant PCM malfunction

HO2S signal stuck rich

DETECTION CONDITION

The PCM monitors the input voltage from the HO2S when the following conditions are met. If the input voltage is more than 0.85 V for 40 s, the PCM determines that the HO2S signal remains rich.

MONITORING CONDITIONS

ECT: more than 70°C {158°F}
Engine speed: more than 1, 500 rpm
MAF amount: more than 10 g/s {1.32 lb/min}
Short term fuel trim: -20-20%
Long term fuel trim: -50-50%
Target A/F feedback system status: feedback control

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

Loose installation of HO2S
Leakage exhaust gas
HO2S malfunction
Fuel line pressure malfunction
- Fuel pump unit malfunction
- Pressure regulator (built-in fuel pump unit) malfunction
Purge solenoid valve malfunction
Fuel injector malfunction
Leakage engine coolant
PCM malfunction

DIAGNOSTIC PROCEDURE

STEP	INSPECTION		ACTION
1	IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA (MODE 2) Is the DTC P2271 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. Are other DTCs present?	Yes	Go to the appropriate DTC inspection. (See DTC TABLE ).
4		No	Go to the next step.
5	INSPECT HO2S Inspect the HO2S. (See HEATED OXYGEN SENSOR (HO2S) INSPECTION ). Is there any malfunction?	Yes	Inspect the following: Loose installation of HO2S Exhaust gas leakage between TWC and HO2S If there is no malfunction detected, replace the HO2S. (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION ). If there is a malfunction detected, repair or replace the malfunctioning part according to the inspection results. Go to Step 10.
5		No	Go to the next step.
6	INSPECT FUEL LINE PRESSURE Perform the "FUEL LINE PRESSURE INSPECTION". (See FUEL LINE PRESSURE INSPECTION ). Is there any malfunction?	Yes	Replace the fuel pump unit, then go to Step 10. (See FUEL PUMP UNIT REMOVAL/INSTALLATION ).
6		No	Go to the next step.
7	INSPECT PURGE SOLENOID VALVE OPERATION Perform the Purge Control System Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION ). Does the purge solenoid valve work properly?	Yes	Go to the next step.
7		No	Repair or replace the malfunctioning part according to the inspection results, then go to Step 10.
8	INSPECT FUEL INJECTOR Inspect the fuel injector. (See FUEL INJECTOR INSPECTION ). Is there any malfunction?	Yes	Replace the fuel injector, then go to Step 10. (See FUEL INJECTOR REMOVAL/INSTALLATION ).
8		No	Go to the next step.
9	INSPECT ENGINE COOLANT PASSAGE FOR ENGINE COOLANT LEAKAGE 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 the next step.
9		No	Go to the next step.
10	VERIFY TROUBLESHOOTING OF DTC P2271 COMPLETED Make sure to reconnect all disconnected connectors. Clear the DTC from the PCM memory using the M-MDS. (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 same as DTC present?	Yes	Replace the PCM, then go to the next step. (See PCM REMOVAL/INSTALLATION ).
10		No	Go to the next step.
11	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 ).
11		No	DTC troubleshooting completed.