CAT 3406E (Prefix 1MM or 2WS) Fault Code: 12 PID: SPN: 111 FMI: 3 Coolant Level voltage high

Posted by PerDiezel Solutions on January 13, 2026

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

•The signal voltage from the coolant level sensor is greater than 4.5 VDC for more than ten seconds.
•The “Coolant Level Sensor” parameter is programmed to “2-wire Float Sensor”.
•The ECM has been powered for at least two seconds.

Probable Causes:

1) Coolant Level Sensor
2) Coolant Level sensor wiring
3) ECM failure

CAT 3406E (Prefix 1MM or 2WS) Fault Code: 12 PID: SPN: 111 FMI: 2 Coolant Level signal invalid

CAT 3406E (Prefix 1MM or 2WS) Fault Code: 01 PID: SPN: 71 FMI: 0 Idle Shutdown Override

CAT 3406E (Prefix 1MM or 2WS) Fault Code: 00 PID: SPN: 247 FMI: 11 Brake Pedal Switch #2 Fault

CAT 3406E (Prefix 1MM or 2WS) Fault Code: 00 PID: SPN: 246 FMI: 11 Brake Pedal Switch #1 Fault

CAT 3406E (Prefix 1MM or 2WS) Fault Code: 00 PID: SPN: 224 FMI: 14 Theft Deterrent Active with Engine Cranking

CAT 3406E (Prefix 1MM or 2WS) Fault Code: 00 PID: SPN: 224 FMI: 11 Theft Deterrent Active

WARNING!