DTC P0172: 1/1 Fuel System Rich: Description

Fuel system rich condition is monitored with engine running in closed loop mode, ambient/battery temperature at more than 20°F (-7°C), and at altitude less than 8000 feet. DTC will set in Powertrain Control Module (PCM) memory when PCM senses fuel system is running too rich on 2 sequential trips. Possible causes for DTC to set are: defective Engine Coolant Temperature (ECT) sensor, engine mechanical problem or fuel pressure out of specification.