Diagnostic procedure

WARNING: This page is about a different car, the 2005 Mazda RX-8. However, it is still accessible from the selected car via links, so may be relevant.

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 the FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS on the repair order, then go to the next step.
2	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.
2		No	Go to the next step.
3	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	If misfire DTC is present, go to Step 8. If other DTC is present, go to the appropriate DTC inspection. (See DTC TABLE .)
3		No	If drive ability concern is present, go to Step 8. If other, 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 the FREEZE FRAME DATA DTC inspection. (See DTC TABLE .)
5	VERIFY CURRENT INPUT SIGNAL STATUS Connect the WDS or equivalent to the DLC-2. Verify the following PIDs. (See PCM INSPECTION .) APP ECT MAF TP VSS Are the PIDs normal?	Yes	Go to the next step.
5		No	Inspect the malfunctioning part according to the inspection results. Then go to Step 11.
6	VERIFY CURRENT INPUT SIGNAL STATUS UNDER FREEZE FRAME DATA CONDITION Connect the WDS or equivalent to the DLC-2. Verify the following PIDs under the FREEZE FRAME DATA condition. (See PCM INSPECTION .) APP ECT MAF TP VSS Are the PIDs normal?	Yes	Go to the next step.
6		No	Inspect the malfunctioning part according to the inspection results. Then go to Step 11.
7	VERIFY CURRENT INPUT SIGNAL STATUS OF FRONT HO2S Connect the WDS or equivalent to the DLC-2. Start the engine and warm it up completely. Access the O2S11 PID. Read the O2S11 PID under the following accelerator pedal conditions (In PARK or NEUTRAL): Less than 1 mA when accelerator pedal is suddenly depressed (rich condition). More than 1 mA just after release of accelerator pedal (lean condition) Is the PID normal?	Yes	Go to the next step.
7		No	Replace the front HO2S, then go to Step 11. (See FRONT HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION .)
8	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 11. (See FUEL PUMP UNIT REMOVAL/INSTALLATION .)
8		No	Go to the next step.
9	INSPECT LONG TERM FUEL TRIM Connect the WDS or equivalent to the DLC-2. Access the LONGFT1 PID. Compare the LONGFT1 PID with recorded FREEZE FRAME DATA at Step 1. Is the LONGFT1 PID above FREEZE FRAME DATA?	Yes	Inspect the purge solenoid valve. (See PURGE SOLENOID VALVE INSPECTION .) If there is any malfunction, replace the purge solenoid valve. (See INTAKE-AIR SYSTEM HOSE ROUTING DIAGRAM .) Then go to Step 11.
9		No	Go to the next step.
10	INSPECT FUEL PUMP SPEED CONTROL OPERATION Perform the "Fuel Pump Speed Control Operation Inspection". (See FUEL PUMP SPEED CONTROL OPERATION INSPECTION .) Is there any malfunction?	Yes	Repair or replace the malfunctioning part according to the inspection results. Then go to the next step.
10		No	Go to the next step.
11	VERIFY TROUBLESHOOTING OF DTC P0172 COMPLETED Make sure to reconnect all disconnected connectors. Clear the DTC from the PCM memory using the WDS or equivalent. Perform the "DRIVE MODE 1". (See OBD-II DRIVE MODE .) Is the PENDING CODE same as the 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 the "AFTER REPAIR PROCEDURE". (See AFTER REPAIR PROCEDURE .) Are any DTCs present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE .)
12		No	DTC troubleshooting completed.