CAT 3406E (Prefix 5DS or 1LW) Fault Code: 21 PID: 232 SPN: FMI: 3 5 Volt Supply voltage high

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

•The 5 volt supply is greater than 5.16 VDC for more than one second.
•The ECM has been powered for at least three seconds.

Sensors that are regulated with 5V: Boot pressure, atmosphere pressure, engine oil pressure, coolant temperature, intake manifold air temperature, fuel temperature

Probable Causes:

1) ECM Connection/Harness
2) Sensor Failure
3) Sensor wiring failure
4) ECM Failure