What the Coolant Temperature Shutdown Switch does
The high coolant temperature switch stops the engine before overheating damages the head gasket, cylinder head or pistons. It closes at its trip temperature and signals the controller to alarm or shut down.
If it fails open, the engine is unprotected; if it trips early, the set shuts down during outages for no real reason.
Signs it needs replacing
- High-temperature shutdown while the gauge shows normal temperature.
- No shutdown although the engine is clearly overheating.
- Corroded or damaged terminal.
Get the right part first time
Send us these on WhatsApp and our engineers will confirm the exact part before you pay:
- Thread size and trip temperature of your current switch.
- A clear photo of the old part, including any label, stamping or part number on it.
Fitting notes
Fit only on a cold engine with the coolant drained below the fitting, using suitable sealant. Test that the alarm and shutdown work. If the engine is genuinely running hot, fix the cooling system — never raise the trip temperature to hide it.
Frequently asked questions
Which trip temperature should I use?+
The rating specified for your engine — commonly 105°C. Do not fit a higher one to stop nuisance trips.
How can I tell if the switch or the engine is at fault?+
Measure the actual coolant temperature with a thermometer or infrared gun when the shutdown happens.
Is this the same as the temperature sender?+
No. The sender drives the gauge; the switch triggers the protection. Many engines have both.