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DTC P0172 [L3]

BME010200100243

DTC P0172 | Fuel trim system too rich
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DETECTION CONDITION | • The PCM monitors short fuel trim (SHRTFT) and long fuel trim (LONGFT) values during OBD DRIVE MODE operation. If fuel trim exceeds preprogrammed criteria, the PCM determines that fuel system is too rich. Diagnostic support note • This is a continuous monitor. (FUEL SYSTEM)
• MIL illuminates if 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 PCM detects the above malfunction condition.
• FREEZE FRAME DATA is available.
• DTC is stored in the PCM memory.
POSSIBLE CAUSE | • Misfire • Front HO2S deterioration • Front HO2S heater malfunction • Pressure regulator malfunction • Fuel pump malfunction
• Fuel return hose clogged
• Purge solenoid valve malfunction
• Purge solenoid hoses improper connection
• PCV valve malfunction

Diagnostic procedure

STEP | INSPECTION | ACTION
--- | --- | ---
1 | VERIFY FREEZE FRAME DATA HAS BEEN RECORDED • Has FREEZE FRAME DATA been recorded? | Yes | Go to the next step.
No | Record FREEZE FRAME DATA on repair order, then go to the next step.
2 | VERIFY RELATED SERVICE INFORMATION AVAILABILITY • Check for related Service Information availability. • Is any related Service Information available? | Yes | Perform repair or diagnosis according to available Service Information. • If vehicle is not repaired, go to the next step.
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 the applicable DTC inspection. (See DTC TABLE [L3].)
No | If driveability concern or rough idle 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.
No | Go to troubleshooting procedures for DTC on FREEZE FRAME DATA.
5 | VERIFY CURRENT INPUT SIGNAL STATUS (KEY TO ON/IDLE) • Access ECT, MAF, TP and VSS PIDs using the WDS or equivalent. • Is there any signal that is far out of specification when key is at ON and engine is running? | Yes | Inspect the sensor and excessive resistance in the related wiring harnesses. Repair or replace if necessary. Then go to Step 11.
No | Go to the next step.
6 | VERIFY CURRENT INPUT SIGNAL STATUS UNDER TROUBLE CONDITION • Inspect same PIDs as is Step 4 while simulating FREEZE FRAME DATA condition. • Is there any input signal which causes drastic changes? | Yes | Inspect the sensor and the related wiring harnesses, and repair or replace it. Then go to Step 11.
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 NEUTRAL). • Is PID reading normal? - Above 0.55 V when the accelerator pedal is suddenly depressed (rich condition).

- Below 0.55 V just after release of the accelerator pedal (lean condition)

Yes
Go to the next step.
No | Replace the front HO2S. Then go to Step 11.
8 | INSPECT FUEL LINE PRESSURE • Turn the ignition switch off. • Connect fuel gauge to fuel pipe. • Start the engine and run it at idle. • Inspect fuel line pressure while the engine running.
(See FUEL LINE PRESSURE INSPECTION [L3].)
• Is fuel line pressure normal?
Yes
Go to the next step.
No | Replace the fuel pump unit, then go to Step 11
9 | INSPECT PURGE SOLENOID VALVE FOR STUCK OPEN • Turn the ignition switch off. • Disconnect both hoses from purge solenoid valve. • Blow air through purge solenoid valve. • Does air blow through? | Yes | Replace the purge solenoid valve. Then go to Step 11.
No | Go to the next step.
10 | INSPECT PCV VALVE OPERATION • Inspect the PCV valve operation. (See PCV VALVE INSPECTION [L3].) • Is the PCV valve normal? | Yes | Go to the next step.
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. • Turn the ignition switch to the ON position (Engine off). • Clear the DTC from the PCM memory using the WDS or equivalent. • Run OBD DRIVE MODE.
(See OBD DRIVE MODE [L3].)
• Is the PENDING CODE of same DTC present?
Yes
Replace the PCM, then go to the next step.
(See PCM REMOVAL/INSTALLATION [L3].)
No | Go to the next step.
12 | VERIFY AFTER REPAIR PROCEDURE • Perform "After Repair Procedure". (See AFTER REPAIR PROCEDURE [L3].) • Is there any DTC present? | Yes | Go to the applicable DTC inspection. (See DTC TABLE [L3].)
No | Troubleshooting completed.