Diagnostic procedure

DTC P0172 DIAGNOSTIC PROCEDURE

STEP	INSPECTION		ACTION
1	VERIFY FREEZE FRAME DATA AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED Have FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS (Fuel system related) been recorded?	Yes	Go to the next step.
1		No	Record FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS on repair order, then go to the next step.
2	VERIFY RELATED REPAIR INFORMATION AVAILABILITY Check for related Technical Service Bulletin(s) repair information availability. Is any related repair information available?	Yes	Perform repair or diagnosis according to available repair information. If vehicle is not repaired, go to the next step.
2		No	Go to the next step.
3	VERIFY RELATED PENDING CODE OR STORED DTCS Turn the ignition switch off, then to the ON position (Engine off). Verify related pending code or stored DTCs. Is other DTCs present?	Yes	Go to appropriate DTC troubleshooting procedures.
3		No	If drive ability concern is present, go to Step 9. If not, go to the next step.
4	IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA Is DTC P0172 on FREEZE FRAME DATA?	Yes	Go to the next step.
4		No	Go to troubleshooting procedures for DTC on FREEZE FRAME DATA.
5	VERIFY CURRENT INPUT SIGNAL STATUS (IGNITION KEY TO ON/IDLE) Access APP1, APP2, ECT, MAF, TP and VSS PIDs using WDS or equivalent. Is there any signal that is far out of specification when ignition switch is ON and engine runs?	Yes	Inspect the sensor and excessive resistance in related wiring harnesses. Repair or replace if necessary. Then go to Step 11.
5		No	Go to the next step.
6	VERIFY CURRENT INPUT SIGNAL STATUS UNDER TROUBLE CONDITION Inspect PID data while simulating FREEZE FRAME DATA condition. Is there any input signal which causes drastic changes?	Yes	Inspect the sensor and related wiring harnesses, and repair or replace it. Then go to Step 11.
6		No	Go to the next step.
7	VERIFY CURRENT INPUT SIGNAL STATUS OF FRONT HO2S Access O2S11 PID using WDS or equivalent. Verify PID while racing engine (in PARK (ATX) or NEUTRAL (MTX)). Is PID reading normal?Except for California emission regulation applicable model Above 0.55 V when accelerator pedal is suddenly depress (rich condition). Below 0.55 V just after release of accelerator pedal (lean condition) California emission regulation applicable model Less than 1 mA when accelerator pedal is suddenly depress (rich condition) More than 1 mA just after release of accelerator pedal (lean condition)	Yes	Go to the next step.
7		No	Replace the front HO2S. Then go to Step 11.
8	INSPECT FUEL LINE PRESSURE Turn the ignition switch off. Inspect fuel line pressure while engine running. (See FUEL LINE PRESSURE INSPECTION .) Is fuel line pressure normal?	Yes	Go to the next step.
8		No	Replace the fuel pump unit, then go to Step 11.
9	INSPECT LONG TERM FUEL TRIM Turn the ignition switch off. Disconnect purge hose from intake manifold and plug opening end of hose and intake manifold. Access LONGFT1 PID. Does it shift to positive value?	Yes	Inspect the purge solenoid valve. Repair or replace it if necessary, then go to Step 11.
9		No	Go to the next step.
10	INSPECT PCV VALVE OPERATION Inspect PCV valve operation. (See POSITIVE CRANKCASE VENTILATION (PCV) VALVE INSPECTION .)	Yes	Go to the next step.
10		No	Replace the PCV valve, then go to the next step.
11	VERIFY TROUBLESHOOTING OF DTC P0172 COMPLETED Make sure to reconnect all disconnected connectors. Clear DTC from PCM memory using WDS or equivalent. Perform the "HO2S heater, HO2S, and TWC Repair Verification Drive Mode". (See OBD-II DRIVE MODE ) Stop vehicle and access ON BOARD READINESS TEST to inspect DRIVE MODE completion status. Verify FUEL_EVAL PID changes to yes. If not, perform the "HO2S heater, HO2S, and TWC Repair Verification Drive Mode" again. Access PENDING CODE. Is the PENDING CODE for this DTC present?	Yes	Replace the PCM, then go to the next step. (See PCM REMOVAL/INSTALLATION .)
11		No	Go to the next step.
12	VERIFY AFTER REPAIR PROCEDURE Perform "AFTER REPAIR PROCEDURE". (See AFTER REPAIR PROCEDURE ) Is there any DTC present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE )
12		No	Troubleshooting completed.