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Home >> Chrysler >> 2009 >> 300 Signature Series >> Repair and Diagnosis >> External Pages >> Different car >> Section 101 (2.4L Engine - DTCS P0128 To P0325) >> Diagnosis And Testing >> P0171-Fuel System 1/1 Lean >> Possible Causes

Possible Causes

WARNING: This page is about a different car, the 2006 Chrysler PT Cruiser. However, it is still accessible from the selected car via links, so may be relevant.
Possible Causes 
RESTRICTED FUEL SUPPLY LINE
FUEL PUMP INLET STRAINER PLUGGED
FUEL PUMP MODULE
O2 SIGNAL CIRCUIT
O2 RETURN CIRCUIT
O2 SENSOR HEATER OPERATION
O2 SENSOR
MAP SENSOR OPERATION
ECT SENSOR OPERATION
ENGINE MECHANICAL PROBLEM
FUEL FILTER/PRESSURE REGULATOR (HIGH)
PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.  (Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE)  .