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Detroit Diesel SPN 111 FMI 1 indicates that the engine coolant level is below the normal operating range.
On Detroit DD13, DD15 and DD16 applications, this fault is associated with the engine coolant level sensor, not primarily with engine coolant temperature.
FMI 1 means the monitored value is valid but below its normal operating range at the most severe level.
What Does SPN 111 FMI 1 Mean?
SPN 111 identifies the Engine Coolant Level parameter.
FMI 1 indicates that the coolant level has fallen below the expected operating range.
Detroit describes this fault as:
Coolant Level Very Low – Coolant Level Below Normal Range
The engine control system continuously monitors the coolant level sensor. If the coolant level falls sufficiently below the acceptable range, SPN 111 FMI 1 may become active.
Symptoms
- Possible symptoms include:
- Check Engine Light
- Low coolant warning
- Low coolant level visible in the surge tank
- Coolant warning displayed on the instrument panel
- Visible coolant leak
- Coolant smell
- Engine temperature may increase if coolant loss continues
- Other coolant-related fault codes may also be present
- The exact warning lamps and engine reaction can vary depending on engine model, model year, vehicle manufacturer and calibration.
Common Causes
Common causes of SPN 111 FMI 1 include:
- Low engine coolant level
- External coolant leak
- Leaking coolant hose or connection
- Radiator or surge tank leak
- Loose or faulty pressure/radiator cap
- Cylinder head gasket coolant leak
- Air compressor head gasket coolant leak
- Heater system coolant leak
- Coolant entering the engine oil
- Faulty engine coolant level sensor
A faulty sensor is possible, but the actual coolant level should always be checked first.
What Should You Check First?
1. Check for Other Fault Codes
Check for additional coolant-level sensor circuit faults or other active engine codes.
If coolant-level circuit codes are present, Detroit recommends diagnosing those faults first.
2. Check the Coolant Level
With the engine cool and the vehicle parked safely, inspect the coolant level in the surge tank.
The coolant should be within the manufacturer’s marked acceptable operating range.
Never remove a pressurized coolant cap from a hot engine.
3. Look for Coolant Leaks
If the coolant level is low, inspect for leaks including:
- Coolant hoses and connections
- Radiator
- Surge tank
- Cylinder head gasket
- Air compressor head gasket
- Cab/heater system
- Radiator or pressure cap
Also inspect for evidence of coolant contamination in the engine oil.
4. Check the Coolant Level Sensor
If the coolant level is correct but SPN 111 FMI 1 continues to return, the engine coolant level sensor may be faulty.
Detroit’s published diagnostic procedure directs technicians to replace the Engine Coolant Level sensor if the coolant is at the proper level and the fault continues to return after the code is cleared and the engine is operated.
Can You Keep Driving With SPN 111 FMI 1?
You should first determine whether the engine is actually low on coolant.
If the coolant level is very low, continuing to operate the engine can eventually cause overheating and serious engine damage.
If the coolant level is normal and there are no overheating symptoms, the fault could be caused by the coolant level sensor. However, the problem should still be diagnosed before extended operation.
Stop the engine if:
- Engine temperature is rapidly increasing
- A STOP ENGINE warning appears
- There is major coolant loss
- Steam or coolant is escaping from the engine
- The engine begins overheating
Never open the cooling system while it is hot and pressurized.
Will SPN 111 FMI 1 Cause a Derate?
Not necessarily.
Detroit’s published GHG17 diagnostic information for SPN 111 FMI 1 lists the engine reaction as None and identifies the Check Engine Light as the associated dash lamp.
However, engine protection behavior can vary by engine generation, vehicle manufacturer and calibration.
More importantly, if actual coolant loss causes the engine to overheat, additional protection faults may activate and can result in reduced power or engine shutdown.
How Do You Fix SPN 111 FMI 1?
The correct repair depends on the cause.
Possible repairs include:
- Add the correct coolant if the level is low
- Repair leaking hoses or fittings
- Repair a leaking radiator or surge tank
- Replace a faulty radiator or pressure cap
- Repair heater-system coolant leaks
- Repair internal coolant leaks
- Repair cylinder head or air compressor gasket leaks
- Replace a faulty engine coolant level sensor
Do not simply replace the coolant level sensor without first verifying the actual coolant level.
Frequently Asked Questions
What does Detroit Diesel SPN 111 FMI 1 mean?
SPN 111 FMI 1 indicates that the engine coolant level is below the normal operating range.
Is SPN 111 FMI 1 a coolant temperature code?
No. SPN 111 relates to engine coolant level.
Engine coolant temperature uses a different SPN.
Can low coolant cause SPN 111 FMI 1?
Yes. Low coolant is the primary condition associated with this fault.
Can a bad coolant level sensor cause SPN 111 FMI 1?
Yes. If the coolant reservoir is properly filled but the code continues to return, a faulty engine coolant level sensor may be responsible.
Can I add coolant and clear the code?
If the coolant is low, correct the coolant level using the proper coolant specified for the engine and inspect the cooling system for leaks.
Simply adding coolant without finding the reason for repeated coolant loss is not a complete repair.
Does SPN 111 FMI 1 mean the engine is overheating?
Not necessarily.
The code reports low coolant level, not coolant temperature.
However, sufficiently low coolant can eventually cause the engine to overheat.
Should I replace the coolant level sensor?
Not automatically.
First verify that the coolant level is correct. If the reservoir is properly filled and the fault continues to return, Detroit’s diagnostic procedure includes replacement of the Engine Coolant Level sensor.
Related codes
Need Immediate Help With This Fault Code?
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Important Notice
This information is provided for general informational and troubleshooting purposes only. Diagnostic procedures, warning lamps and engine protection responses may vary depending on the Detroit engine model, emissions generation, software calibration and vehicle manufacturer.
Always verify active faults using current Detroit service information or DiagnosticLink and follow the manufacturer’s diagnostic procedures before replacing components.