Fuel System 1/1 Under Correction of Fuel Mixture (Off Idle)

(P0171) FUEL SYSTEM 1/1 UNDER CORRECTION OF FUEL MIXTURE (OFF IDLE)








When Monitored and Set Condition
^ When Monitored: With the engine running in closed loop mode, the ambient/battery temperature above -70°C (20°F), altitude below 2590 m (8500 ft). and fuel level greater than 15%.
^ Set Condition: If the PCM multiplies short term compensation by long term adaptive and a certain percentage is exceeded for two trips, the MIL illuminates and a trouble code is stored.

POSSIBLE CAUSES
- RESTRICTED FUEL SUPPLY LINE
- FUEL PUMP INLET STRAINER PLUGGED
- 02 SENSOR SIGNAL CIRCUIT
- 02 SENSOR GROUND CIRCUIT
- 02 SENSOR HEATER OPERATION
- MANIFOLD ABSOLUTE PRESSURE SENSOR OPERATION
- ENGINE COOLANT TEMPERATURE SENSOR OPERATION
- ENGINE MECHANICAL PROBLEM
- 02 SENSOR
- FUEL PUMP
- FUEL CONTAMINATION/EXHAUST LEAK



Diagnostic Test
1. CHECK FOR CURRENT DTC





Turn the ignition on. With the DRBIII, read PCM DTCs.
Is this DTC present?
Yes >> For complete diagnosis of this DTC, refer to (P0172) FUEL SYSTEM 1/1 LEAN CONTROL BELOW LIMIT (AT LOAD). Fuel System 1/1 Lean Control Below Limit (at Load)
No >> Go To 2

2. INTERMITTENT WIRING AND CONNECTORS
The conditions necessary to set this DTC are not present at this time.

Note: Check connectors - Clean/repair as necessary. Poor pin to terminal connections can set DTCs. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors specific to this DTC. Wiggle the wires while checking for shorts and open circuits.

Note: Check for any Technical Service Bulletins that may apply.

Were there any problems found?
Yes >> Repair as necessary. Perform POWERTRAIN VERIFICATION TEST - VER 2 Powertrain Verification Test - Ver 2.
No >> The condition that caused this DTC to set is currently not present. Inspect the related wiring harness for a possible intermittent condition.