P0171

Tests 1 - 3:

Tests 4 - 7:

Tests 8 - 11:

Tests 12 - 14:

Tests 15 - 17:

SYMPTOM
P0171-1/1 FUEL SYSTEM LEAN

WHEN MONITORED
With the engine running in closed loop mode, the ambient/battery temperature above 20 °F and altitude below 8000 ft.

SET CONDITION
If the PCM multiplies short term compensation by long term adaptive and a certain percentage is exceeded for two trips, a freeze frame is stored, the MIL illuminates and a trouble code is stored.

POSSIBLE CAUSES
- Intermittent condition
- Fuel pressure out of specs
- Restricted fuel supply line
- Fuel pump inlet strainer plugged
- Fuel pump module
- Low fuel pump volume
- O2 Sensor
- O2 Sensor signal circuit shorted to ground
- O2 Sensor heater operation
- TPS voltage greater than 0.92 Volts with throttle closed
- Throttle position sensor sweep
- MAP sensor operation
- ECT sensor operation
- Engine mechanical problem
- Fuel filter/pressure regulator
- PCM