SPN 110 FMI 0
STOP
High temperature
Coolant is running too hot: engine damage risk.
SPN 110 FMI 0: Coolant is running too hot: engine damage risk. Stop: this is a stop-now code. Park safely and do not keep driving until it is checked.
Mechanical · Cooling
What it means
Coolant temperature went above the engine protection threshold. The ECM will pull power and may shut the engine down. Park safely and let it cool before opening anything in the cooling system.
Most likely causes
Low coolant level or a leak
Very likely
Radiator or CAC plugged with debris
Very likely
Fan clutch not engaging
Likely
Thermostat stuck closed
Likely
Tests, cheapest and most decisive first
1. Check coolant level cold and look for leaks
Expected result: Level at the mark, no leak traces
2. Inspect the radiator and CAC against a light
Expected result: Clean fins, light visible through the core
3. Verify fan engagement
Expected result: Fan engages when commanded
Tool: J1939 scanner
Read it off your own dash
Take one photo and DERATE tells you whether you can keep driving.
DERATEDERATE assists. It does not replace inspection by a qualified technician.