Originally Posted by alaxfire

From the manual :

When Monitored and Set Condition
² When Monitored: With the engine running in closed loop mode, the ambient/battery temperature above -7°C (20°F),
altitude below 2590m (8500 ft). and fuel level greater than 15%.
² 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 STRAINER PLUGGED
O2 SENSOR SIGNAL CIRCUIT
O2 SENSOR GROUND CIRCUIT
O2 SENSOR HEATER OPERATION
MANIFOLD ABSOLUTE PRESSURE SENSOR OPERATION
ENGINE COOLANT TEMPERATURE SENSOR OPERATION
ENGINE MECHANICAL PROBLEM
O2 SENSOR
FUEL PUMP
FUEL CONTAMINATION/EXHAUST LEAK

I'd start with replacing the fuel filter .....