P0275

Diagnostic Chart:

Wiring Diagram:

Circuit Description

The PCM has the ability to increase and decrease the amount of fuel to each cylinder to provide smooth idle operation. If the PCM decides that the fuel reduction amount to a specific cylinder exceeds define limits, this DTC will set. This DTC only monitors fuel reduction.


Conditions for Setting the DTC

^ Engine at idle greater than a total of 90 seconds.

^ All engine misfire DTCs ran and passed.

^ Engine coolant at normal temperatures.

^ Cylinder fault must be constant.

^ Amount of fuel reduction for a specific cylinder exceeds limits (internal to PCM).

^ Conditions met for 2 seconds.

Action Taken When the DTC Sets

^ The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

^ The PCM records the operating conditions at the time the diagnostic fails. This information stores in the Failure Records.


Conditions for Clearing the MIL/DTC

^ A History DTC will clear when forty consecutive warm-up cycles that the diagnostic does not fail (coolant temperature has risen 5°C (40°F) from start up coolant temperature and engine coolant temperature exceeds 71°C (160°F) that same ignition cycle.

^ Use of a Scan tool


Diagnostic Aids

Injector balance test on scan tool should be used to confirm fault cylinder problems. Scan tool will cutout specific cylinder requested. It is possible that if a cylinder balance fault has been detected and engine has been running for a long time, the PCM will try to increase or decrease fuel in other cylinders to compensate for a rough idle which can cause multiple cylinder balance DTCs to set. The scan tool snap shot mode can be used to properly identify the suspected cylinder. The most likely cause of cylinder balance DTCs are malfunctioning nozzles.

If multiple cylinder balance DTCs are set and no problem is found, check for the following:

^ Pinched or restricted fuel feed lines between fuel tank and fuel injection pump

^ Restricted fuel filter


Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

2. This step will properly identify a suspected cylinder by looking for a RPM drop (if RPM drops, cylinder is contributing, if not cylinder is not contributing).