DTC P0171: Notes
DTC P0171 DETECTION & CONDITION POSSIBLE CAUSES
| DTC P0171 |
System too lean |
| DETECTION CONDITION |
- The PCM monitors the short term fuel trim (SHRTFT) and long term fuel trim (LONGFT) when under closed loop fuel control. If the fuel trim is more than the specification, the PCM determines that the 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 the first drive cycle.
- FREEZE FRAME DATA is available.
- The DTC is stored in the PCM memory.
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| POSSIBLE CAUSE |
- Front HO2S malfunction
- Excess air suction in intake-air system
- Leakage exhaust gas
- MAF sensor malfunction
- Fuel line pressure malfunction
- Fuel pump unit malfunction
- Leakage fuel
- Ignition system malfunction
- High-tension lead malfunction
- Incorrect power supply to ignition coil
- Ignition coil malfunction
- Insufficient compression
- Metering oil pump malfunction
- Engine oil condition malfunction
- Increased oil pressure
- Oil passage malfunction
- Engine malfunction
- Fuel injector malfunction
- PCM malfunction
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