Detailed guide for SPN 111 FMI 1
Back to top ↑What SPN 111 FMI 1 means
SPN 111 identifies engine coolant level. FMI 1 indicates coolant level below the normal operating range at the most severe level.
Detroit troubleshooting information describes SPN 111 FMI 1 as a coolant-level-low condition.
What to check first
When the engine is cool and safe to service, check the coolant level in the surge tank or reservoir using the manufacturer's specified level marks.
If coolant is low, inspect the system for external leaks. Depending on the engine, also investigate possible internal leakage, reservoir-cap problems or other causes of coolant loss.
If coolant level is correct but the fault remains active, inspect and test the engine coolant level sensor and its circuit.
Important
Do not simply add coolant repeatedly without finding the reason for coolant loss. Low coolant can lead to overheating and engine damage.
The exact sensor arrangement and protection strategy differ by vehicle and engine manufacturer.
Mechanic community notes for SPN 111 FMI 1
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