Fuel System 1/1 Over Correction of Fuel Mixture (at Idle)

(P0172) FUEL SYSTEM 1/1 OVER CORRECTION OF FUEL MIXTURE (AT IDLE)








When Monitored and Set Condition
^ When Monitored: With the engine running in closed loop mode, the ambient/battery temperature above -7°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
- EVAP PURGE SOLENOID OPERATION
- 02 SIGNAL CIRCUIT
- RESTRICTED FUEL SUPPLY LINE
- FUEL PUMP INLET STRAINER PLUGGED
- 02 SENSOR GROUND CIRCUIT
- MANIFOLD ABSOLUTE PRESSURE SENSOR OPERATION
- ENGINE COOLANT TEMPERATURE SENSOR OPERATION
- 02 SENSOR
- ENGINE MECHANICAL PROBLEM
- FUEL FILTER/PRESSURE REGULATOR
- POWERTRAIN CONTROL MODULE



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 (P0171) FUEL SYSTEM 1/1 RICH CONTROL OVER LIMIT (AT LOAD). Fuel System 1/1 Rich Control Over 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.