Electronic Control System ISM and QSM11 Engines – FAULT CODE 951

Cylinder Power Imbalance


Overview

CODE REASON EFFECT
Fault Code: 951
PID: P166
SPN: 166
FMI: 2/2
LAMP: None
SRT: 

Cylinder Power Imbalance Between Cylinders. A power imbalance between cylinders was detected by the electronic control module (ECM).

Engine can have rough idle or misfire.

Cylinder Power Imbalance
SMALL | MEDIUM | LARGE

Circuit Description

The ECM calculates the power output of each cylinder at engine idle speeds.

Component Location

The ECM is located on the fuel system side of the engine. It is attached at the cylinder head between cylinders 2 and 3.

Shop Talk

At engine idle speeds, the ECM measures the instantaneous acceleration of each cylinder as it fires, to determine the cylinder’s power. The ECM adjusts fueling to individual cylinders if the imbalance is within pre-defined limits. If the imbalance is greater than the pre-defined limits, Fault Code 951 will be set active.

Refer to Troubleshooting Fault Code t05-951

Last Modified:  02-Sep-2010