CM870 and ISX Engines – FAULT CODE 343

Electronic Control Module (ECM)


Fault Code: 343
PID: S254
SPN: 629
FMI: 12/12
LAMP: Amber

Engine Control Module – Warning internal hardware failure. Internal ECM error.

Possibly none on performance, or severe derate.

Electronic Control Module

Circuit Description

The ECM is a computer that is responsible for engine control, diagnostics, and user features.

Component Location

The ECM is bolted to the intake side of the cylinder head between the air inlet horn and the front of the engine. Refer to Section E for a detailed component location view.

Shop Talk

This fault code can only be caused by an internal ECM problem. Repairs are not possible for the ECM.

Refer to Troubleshooting Fault Code t05-343

Last Modified:  01-Sep-2010