P0171

Test 1 - 3:

Test 4 - 6:

Test 7 - 9:

Test 10 - 13:

Test 14:

SYMPTOM
P0171-FUEL SYSTEM 1/1 LEAN

WHEN MONITORED
With the engine running in closed loop mode, the ambient/battery temperature above 20 deg. F and altitude below 8500 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. Two Trip Fault. Three good trips to turn off the MIL.

POSSIBLE CAUSES
- Good trip equal to zero
- Restricted fuel supply line
- Fuel pump inlet strainer plugged
- Fuel pump module
- O2 sensor
- O2 signal circuit
- O2 return circuit
- O2 sensor heater operation
- MAP sensor operation
- ECT sensor operation
- Engine mechanical problem
- Fuel filter/pressure regulator (high)
- PCM