My coolant Level gauge just started rising until it got 130° and I turned on the AC and it dropped straight away back to 90°, just wondering if anybody else has had this issue? And if so could just be the sensor or am I looking at something else? 

Do you mean the temperature gauge?

1 minute ago, ords said:

Do you mean the temperature gauge?

That is exactly what I meant haha! I didn't proof read my post! 

If It's a diesel then it's a well known problem.

 

Read  The Mk3 Octavia TDI water pump thread  at the top of the page