DTC P0171:00: Notes
DTC P0171:00 (L3 WITH TC) DETECTION CONDITION & POSSIBLE CAUSES
| DTC P0171:00 |
Fuel trim system too lean |
| DETECTION CONDITION |
- The PCM monitors the short term fuel trim (SHRTFT) and long term fuel trim (LONGFT) values when closed loop fuel control. If the LONGFT and the sum total of these fuel trims or SHRTFT exceed preprogrammed criteria, the PCM determines that the fuel system is too lean.
Diagnostic support note
- This is a continuous monitor (fuel system).
- 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 first drive cycle.
- FREEZE FRAME DATA (Mode 2)/Snapshot data is available.
- The DTC is stored in the PCM memory.
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| POSSIBLE CAUSE |
- Erratic signal to PCM
- APP sensor signal malfunction
- ECT sensor No. 1 signal malfunction
- MAF sensor signal malfunction
- TP sensor signal malfunction
- VSS signal malfunction
- Related connector or terminals malfunction
- Related wiring harness malfunction
- A/F sensor heater malfunction
- A/F sensor looseness
- Exhaust system leakage
- A/F sensor deterioration
- MAF sensor malfunction
- Air suction in intake air system
- Improper operation of purge control system
- Purge solenoid valve malfunction (stuck open)
- Improper connection of purge solenoid hoses
- Improper operation of variable valve timing control system
- High-pressure side fuel delivery system malfunction
- Fuel pressure sensor (built-in fuel delivery pipe) malfunction
- Relief valve (built-in fuel delivery pipe) malfunction
- Spill valve control solenoid valve (built-in high pressure fuel pump) malfunction
- High pressure fuel pump malfunction
- Low-pressure side fuel delivery system malfunction
- Fuel pressure regulator (built-in fuel pump unit) malfunction
- Fuel pump unit malfunction
- Fuel filter clogging
- Fuel leakage on fuel line (between fuel pump unit and high pressure fuel pump)
- Ignition system malfunction
- Spark plug malfunction
- Ignition coil malfunction
- Ignition coil related wiring harness malfunction
- Insufficient engine compression
- Improper operation of fuel injector
- Misfire
- Fuel runout
- PCM malfunction
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