CAT 3126B Fault Code: 231-12 PID: Flash Code 00 SPN: FMI: J1939 Device Not Responding

Posted by PerDiezel Solutions on January 12, 2026

The Engine Control Module (ECM) detects the following conditions:

•The ECM is unsuccessful in receiving a message from a J1939 source.
•The ECM is not receiving a valid message from a J1939 source

The power train data link is designed to offer electronically controlled Anti-Lock Brakes (ABS), traction control systems, and/or transmission controls. This is accomplished by a momentary reduction of engine rpm and/or engine torque, that is triggered by a signal from an off-engine control module for the ABS, the traction control, or the transmission. An off-engine control module is a control module that is not part of theCaterpillar engine control system.

Possible Causes:

1) ECM Connection/Harness
2) Other devices on the J1939 (ABS, Body Controller, Transmission, etc…) are failing causing the issue
3) Improper programming in ECM
4) ECM Failure

CAT 3126B Fault Code: 224-14 PID: Flash Code 00 SPN: FMI: Theft Deterent Active with Engine Cranking

CAT 3126B Fault Code: 224-11 PID: Flash Code 00 SPN: FMI: Theft Deterent Active

CAT 3126B Fault Code: 96-04 PID: Flash Code 00 SPN: 96 FMI: 4 Fuel Level Voltage Low

CAT 3126B Fault Code: 96-03 PID: Flash Code 00 SPN: 96 FMI: 3 Fuel Level Voltage High

CAT 3126B Fault Code: 247-11 PID: Flash Code 00 SPN: FMI: Service Brake Switch #2 Fault

CAT 3126B Fault Code: 246-11 PID: Flash Code 00 SPN: FMI: Service Brake Switch #1 Fault

WARNING!