I assume its a coolant sensor?

How do I locate it and how do I test it?

Thanks in advance

Its a BKD engine if that helps

Found this on here. Think there are two on the BKD engine.

https://www.briskoda.net/forums/topic/245159-engine-coolant-temperature-sensor/

Think you can test with a multimeter when cold and then in hot water. The resistance should change but not sure if it drops or rises when hot.

Thanks I had seen that post but still cant fine the sensor!

On side of cylinder head towards battery under the MAF ducting. Fairly easy to replace but you'll lose some coolant. Pop an ice cream tub under it to catch coolant.

Bosch or Febi equivalent.

Thanks Its currently not on so I will keep a close eye on it

It could also be a connector or wiring fault in the sensor circuit.