P0171 1/1 Fuel System Lean

SYMPTOM LIST
P-0171 1/1 FUEL SYSTEM LEAN

TEST NOTE:
All symptoms listed above are diagnosed using the same tests. The title for the tests will be P-0171 1/1 FUEL SYSTEM LEAN.

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

SET CONDITION
PCM conducts test to determine if fuel system is running too lean. If this happens for 2 trips, MIL illuminates & a trouble code is stored. MIL remains on for more than one trip but goes out if conditions that set code are not found on subsequent trips.

POSSIBLE CAUSES
- Coolant sensor calibration failure
- Engine mechanical problem
- Fuel pressure out of specification
- Upstream O2 sensor heater defect
- Fuel system rich or lean does not reoccur