P0171

Test 1 - 3:

Test 4 - 9:

Test 10 - 12:

Test 13 - 15:

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
- Good trip equal to zero
- Fuel pressure out of specs
- Restricted fuel supply line
- Fuel pump inlet strainer plugged
- Fuel pump module
- O2 sensor
- O2 sensor signal circuit shorted to ground
- O2 sensor heater operation
- TP sensor voltage greater than 0.92 of a volt with throttle closed
- TP sensor sweep
- MAP sensor operation
- ECT sensor operation
- Engine mechanical problem
- Fuel filter/pressure regulator
- Intermittent condition
- PCM