Mack MP8 SPN 110 FMI 0 �?Coolant Temperature Above Normal (High)

Code Details

Plain-English Meaning

The Mack MP8 cooling system is designed to maintain engine temperature within an optimal operating range. When coolant temperature rises above the warning threshold, the heat being produced exceeds the system's cooling capacity. This needs to be investigated immediately to prevent cylinder head warping, head gasket failure, or piston damage. On Mack Anthem, Pinnacle, and Granite trucks with the MP8, VCADS Pro monitors coolant temperature alongside fan clutch state and EGR cooler outlet temperature. A partial coolant system blockage from scale buildup is more difficult to detect than a failed thermostat because the engine warms normally to operating temperature but cannot shed heat fast enough under sustained high-load conditions. A coolant flow test — measuring pressure drop across the coolant circuit — can identify restriction that a temperature-only check would miss. VCADS Pro records the peak coolant temperature during the fault event.

SPN 110 FMI 0 indicates Engine Coolant Temperature above normal on the J1939 bus. On Mack MP8 engines with the EMS3 control system, the ECM manages the fan clutch engagement and can trigger engine protection derates. VCADS Pro provides coolant temperature, fan engagement data, and thermostat status in live data mode. The fault may co-occur with SPN 1569 FMI 31 if the protection derate has activated.

Common Symptoms

• High coolant temperature warning lamp
• Engine protection derate may be concurrent
• Steam or coolant smell if temperature is critically high

Possible Causes

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

• Low coolant level from a leak or high consumption
• Thermostat stuck in the closed position
• Radiator plugged by insects or debris
• Fan clutch not engaging properly
• Water pump worn or failing
• EGR cooler failure adding excess heat to the coolant circuit

First Checks

• Check coolant level in the overflow tank
• Inspect the radiator face and CAC (charge air cooler) face for debris or bug screens
• Connect VCADS Pro and check coolant temperature and fan engagement duty cycle
• Inspect for external coolant leaks from hoses, pump, and radiator
• Review the fault event snapshot in VCADS Pro — note vehicle load, speed, and peak coolant temperature at fault time
• Conduct a coolant circuit flow test to detect partial blockage from scale that does not prevent cold-start warmup

Can I Keep Driving?

Reduce load and stop if temperature continues rising. Overheating an MP8 risks expensive internal engine damage.

Related Lookup Pages

• SPN 110 topic page
• FMI 0 explanation
• Search this code