Do not get left in the dark!
Generac
Engine coolant too hot. Check coolant level, radiator, thermostat, and fan.
Need a technician? Skip the troubleshooting — open a service ticket and we'll handle it.
⚠ SAFETY FIRST: Disconnect battery (negative lead first) before inspecting internal components. Never work on a generator that may auto-start.
Overview
Engine coolant too hot. Check coolant level, radiator, thermostat, and fan.
Low coolant level — insufficient coolant to absorb and transfer heat
Blocked or clogged radiator (dirt, insects, debris on fins)
Failed thermostat stuck closed — coolant not circulating to radiator
Failed cooling fan or fan belt
Failed water pump — coolant not circulating
Air lock in the cooling system (bubble blocking coolant flow)
Radiator hose collapse under vacuum
Generator overloaded in high ambient temperature
Faulty coolant temperature sensor (false alarm)
Step-by-step workflow
⚠️ HIGH TEMPERATURE DANGER: Allow at least 45–60 minutes of cooling before inspecting any cooling system components. Do not open the radiator cap.
Once fully cooled, check the overflow reservoir. Low coolant is the most common cause of high coolant temperature.
The radiator must be clean to dissipate heat effectively. Insects, cottonwood, leaves, and dirt clogging the fins dramatically reduce cooling capacity.
A stuck-closed thermostat prevents coolant from flowing through the radiator. The engine overheats even with correct coolant level and a clean radiator.
The radiator fan must run any time coolant temperature exceeds the set point. A failed fan or broken/slipped belt will cause rapid overheating under load.
Only after full cool-down and addressing the root cause should you clear the fault and restart.
After reset
The code cleared and the unit returned to standby. Log the incident, confirm ready-to-run status, and monitor the next exercise cycle.
If the code returns immediately, stop resetting and move into service. The issue likely needs inspection of wiring, switches, or a controller-level component.
Prevention
Inspect overflow reservoir monthly. Consistent level loss indicates a slow but serious leak.
Blow out debris from radiator fins every spring and fall — especially in cottonwood or high-pollen areas.
Thermostats fail silently. Proactive replacement prevents unexpected overheating shutdowns.
A&A Power Generators inspects the entire cooling system at every service visit. 888-991-4500
On hot days, keep generator load below 70% of rated capacity — ambient heat reduces cooling effectiveness.
Receive High Coolant Temperature alarms instantly via the Generac Mobile Link app.
Let A&A Power Generators handle all preventative maintenance for your generator.
Still need help?
If the issue persists after following the workflow, route the unit into ticket, appointment, or consultation support so the team can take over with the right service path.
