Suzuki Swift - Temperature gauge hitting red at 60mph - RobSHH

I would really apprecaite some assistance

When travelling around at less than 50mph, the temperaure gauge on my 56 Suzuki Swift (VVTS GLX 1.5 petrol) shows normal temperature (i.e. sits at around half way on the guage).

If I go over 60mph, it suddenly shoots up and can reach the red. If I slow down again (i.e. back down from 60mph), the guage rapidly drops down again.

There is no obvious steam or smoke coming from the engine or exhaust. I've also had it services in the time that the symptons started with nothing untowards found.

I am suspecting it to be the sensor, though would appreciate the thoughts of those in the know. On the basis that it is the sensor, I'm assuming that it would be pretty simple to replace??

MTIA

Suzuki Swift - Temperature gauge hitting red at 60mph - elekie&a/c doctor
Unlikely to be the sensor.I would get the cooling system checked for flow and also the thermostat operation.I assume the coolant level has been checked?
Suzuki Swift - Temperature gauge hitting red at 60mph - edlithgow

You might have air in your cooling system, reducing its efficiency.

You might have a compromised head gasket, putting hot combustion gases into the cooling system.

Any sign of venting or spitting of coolant from the reservoir? (This is more likely with an un-pressurised reservoir. I don't know what type is fitted to the Swift.)

A garage could run a check for combustion gases leaking into the cooling system at high revs.

Suzuki Swift - Temperature gauge hitting red at 60mph - Gibbo_Wirral

I had the exact same problem on a Peugeot 307, as soon as you went over 70mph it would fly into the red then drop back down. It was a faulty (or just EOL - it was ten years old) sensor. Cheap fix at a tenner.