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DTC P2178: Notes

DTC P2178 [L3] CHART

DTC P2178

Fuel system too rich at off idle

DETECTION CONDITION

PCM monitors short term fuel trim (SHRTFT), long term fuel trim (LONGFT) during closed loop fuel control at off-idle. If the LONGFT and the sum total of these fuel trims exceed preprogrammed criteria. PCM determines that fuel system is too rich at off-idle.

Diagnostic support note

This is a continuous monitor (Fuel system).
MIL illuminates if the PCM detects the above malfunction condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.
PENDING CODE is available if the PCM detects the above malfunction condition during the first drive cycle.
FREEZE FRAME DATA is available.
DTC is stored in the PCM memory.

POSSIBLE CAUSE

Misfire
Front HO2S deterioration
Front HO2S heater malfunction
MAF sensor malfunction
Pressure regulator (built-in fuel injection pump) malfunction
Fuel pump malfunction
EGR valve improper operation
VTCS improper operation
Purge solenoid valve improper operation
Purge solenoid valve malfunction (stuck open)
Purge solenoid hoses improper connection
PCV valve malfunction
Variable valve timing control system improper operation
PCM malfunction