International A26 SPN 111 FMI 1 — Coolant Level Low

Code Details

Plain-English Meaning

The International A26 cooling system monitors the engine coolant level through a sensor in the coolant expansion or deaeration tank. When coolant drops below the minimum safe threshold, the ECM sets SPN 111 FMI 1 and alerts the operator. The A26 is a modern inline-six heavy-duty engine used in LT and RH Series trucks for linehaul and vocational applications where consistent thermal management is important for engine longevity and performance. A reduction in coolant level below the safe minimum compromises the cooling system's ability to manage the heat generated under high-load conditions. Cooling system leaks on the A26 most commonly originate at hose connections, the radiator, or the water pump. Internal leakage through the head gasket is a more severe condition that requires prompt attention. A faulty coolant level sensor can also trigger this code without actual coolant loss, so physical verification is always the first step.

SPN 111 is Coolant Level; FMI 1 indicates a valid signal below the normal operational range. On the A26, the coolant level sensor is positioned in the expansion tank and reports to the ECM. International Servicemaxx provides the coolant level sensor live status, freeze-frame data at fault set, and related cooling system parameter data. If SPN 110 FMI 0 is also stored, the coolant loss has already affected engine temperature. Servicemaxx freeze-frame data can show the coolant temperature and engine load at the time SPN 111 FMI 1 was first detected, providing context for whether the engine was operating in a thermally stressed condition when the low level was first detected.

Common Symptoms

• Low coolant warning lamp on the instrument panel
• Coolant expansion tank level visually low on inspection
• Coolant residue or wet spots at hose connections or the radiator area
• White exhaust smoke or coolant smell from the exhaust if coolant is internally consumed
• Engine temperature rising if the cooling capacity is reduced

Possible Causes

Possible causes may include the items below. The list is not a parts diagnosis.

• External coolant leak at hose connections, clamps, or fittings
• Radiator core or tank leak from corrosion or impact damage
• Water pump seal failure
• Head gasket failure allowing coolant into the combustion chamber
• EGR cooler internal failure directing coolant into the exhaust
• Coolant level sensor failure or wiring fault producing a false low signal

First Checks

• Check the coolant expansion tank level with the engine cold and compare against the min/max marks
• Inspect accessible hose connections, the radiator, and the water pump for visible coolant leakage or dried coolant residue
• Add the correct pre-mixed coolant to restore the level and monitor for recurrence over the following hours of operation
• Connect International Servicemaxx to verify the coolant level sensor is reading correctly and to check for related cooling system fault codes
• If no external leak is found and coolant consumption continues, perform a combustion block test and inspect the engine oil for signs of coolant contamination indicating internal leakage

Can I Keep Driving?

Low coolant is a serious condition on the A26. The risk of overheating is elevated under high-load linehaul or vocational conditions. Top up the coolant and investigate the source before resuming high-load operation.

Related Lookup Pages

• SPN 111 topic page
• FMI 1 explanation
• Search this code