Fuel System Monitor
OBD SYSTEM DESCRIPTION - FUEL SYSTEM MONITORSystem Description / Monitoring Procedure
As fuel system components age or otherwise change over the life of the vehicle, the adaptive fuel strategy learns deviations from stoichiometry while running in closed loop fuel. These learned corrections are stored in keep alive memory as long term fuel trim corrections. They may be stored continue to change beyond normal limits or if a malfunction occurs, the long term fuel trim values will reach a calibratable rich or lean limit where the adaptive fuel strategy is no longer allowed to compensate for additional fuel system changes. Long term fuel trim corrections at their limits, in conjunction with a calibratable deviation in short term fuel trim, indicate a rich or lean fuel system malfunction.
DTC Description / Detecting Condition / Confirmation Procedure
P0171, P0172
Refer to DTC P0171 / P0172: System Too Lean / Rich. P0171 P0172
Fuel System Monitor