CAT 3406E (Prefix 1MM or 2WS) Fault Code: 16 PID: SPN: 173 FMI: 0 High Exhaust Gas Temperature Derate

This code indicates that the engine has been derated in order to prevent excessive exhaust temperatures. The engine will only be derated to a level that will allow the exhaust temperature to be lowered to an acceptable level. This code will be logged once the engine has been derated by more than 4%. This is not a code, but an event being logged . Talk to the driver to see if the engine was running under heavy loads or climbing steep hills.