DTC P0172: System Too Rich (Bank 1)

WARNING: This page is about a different car, the 2006 Mercury Mariner and 2006 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.

P0172 - SYSTEM TOO RICH (BANK 1)

Description:	The adaptive fuel strategy continuously monitors the fuel delivery hardware. The test fails when the adaptive fuel tables reach a lean calibrated limit. Refer to FUEL TRIM for more information.
Possible Causes:	Air Measurement System. MAF sensor (contaminated, damaged, or corroded connector). Fuel System. Fuel Pressure Regulator (vacuum hose off, diaphragm leak, malfunctioning). Leaking fuel injectors. Fuel return line restricted. Fuel rail pressure sensor (incorrect reading). EVAP canister purge valve leak (when canister is full). Base engine. Engine oil contamination.
Diagnostic Aids:	View freeze frame data to determine the operating conditions when the DTC was set. Observe the LONGFT1 PID. Refer to , ADAPTIVE FUEL DTCS DIAGNOSTIC TECHNIQUES for more information.
Application	Key On Engine Off	Key On Engine Running	Continuous Memory
All	-	-	GO to Pinpoint Test H .