I've had strange things happening with the temperature gauge recently. Every now and then the needle will dive to zero then come back up to where it was previously, slowly. The thermostat was not working so that got changed, but the needle still does it's own thing occasionally. Is this likely to be the sender or the gauge? No other gauges are affected.

Will be the Coolant temp sensor m8 ...

get a genuine one from skoda/TPS...

Don't be tempted by the other cheepo ones they don't last 6months

Cheers, I thought so.