SPN 111 — Coolant Level
System: Cooling
Coolant level in the expansion tank or radiator, from a level probe or switch.
Can I keep running it?
HIGH — limit use, diagnose now
Low coolant can lead to overheating and head damage. Top off and find the leak before working hard.
Likely causes
- Coolant leak (hoses, radiator, water pump, EGR cooler)
- Coolant level sensor dirty or failed
- Wiring fault
Checks & fixes (easiest first)
- Check actual level when cold
- Look for external leaks and white exhaust smoke
- Clean or test the level probe
- Pressure-test the cooling system
Common FMIs with SPN 111
- SPN 111 FMI 1Value too low (most severe)
- SPN 111 FMI 3Voltage above normal or shorted high
- SPN 111 FMI 4Voltage below normal or shorted low
- SPN 111 FMI 17Value too low (least severe)
- SPN 111 FMI 18Value too low (moderately severe)
Related codes
- SPN 110Engine Coolant Temperature
FAQ
What does SPN 111 mean?
SPN 111 is Coolant Level. Coolant level in the expansion tank or radiator, from a level probe or switch.
Can I keep running with SPN 111?
Low coolant can lead to overheating and head damage. Top off and find the leak before working hard.
What causes SPN 111?
Coolant leak (hoses, radiator, water pump, EGR cooler); Coolant level sensor dirty or failed; Wiring fault.