Help!!!! Hi I have a Mk3 64 plate diesel Octavia VRS which I’ve had for about 4mnths. Recently I have started having an issue.I commute into London everyday and just as the car is warm (90deg water temp) I’m going ~70mph on the A1M. Everyday the the temp keeps on rising all the way to 130deg C and then alarms. If I reduce the speed to ~45/50 mpg is comes down to 90 deg C and then regardless of me speeding back up, it seems to be fine. On the return journey when I’m hoing much slower when the car is first up to temp, I have no issues. It seems a once a day issue. It’s in the garage as I thought it was a quick sensor change but they seem to be very confused by it. They were thinking it was the water pump which is obviously a much bigger job and were struggling to work out where the sensor was. It is my local garage (as Skoda if a fair distance away) who have always been excellent in the past. 

Any constructive words of wisdom would be welcomed. Cheers. 

Hello Sparky, take a look at the engine overheating section - it could be a water pump issue, they have a moving sleeve which can fail and stick closed. 

Very very common on earlier Mk3 Octavia diesels. Search overheating and you'll find heaps of info, e.g.: