P0171

Test 1 - 3:

Test 4 - 7:

Test 8 - 10:

Test 11 - 13:

Test 14 - 15:

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.

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
- Throttle position sensor voltage greater than 0.92 volts with throttle closed
- Throttle position sensor sweep
- MAP sensor
- ECT sensor
- Engine mechanical problem
- Fuel filter/pressure regulator (high)
- PCM