Some background history.Yes definitely a silly mistake. It’s not connected yet I’m going to leave it until the morning. Thanks for your advice mate. One last question, how would I know if I had a dodgy water pump?
SEAT (or VAG Group) in their inifinate wisdom created an electronic water pump that allowed the car to warm up quicker and be better with emissions (and put a big tick in that box). It had a shroud/cover that moved up and down over the impeller to alter the water flow. It reduced water flow to allow the car to warm up quicker and then allowed more water to flow when the car got hotter.
The problem is the shroud starts to stick and can cause not enough water to get round the system and you get an overheat.
The biggest challenge was that they were intermittent and it was hard to know if it was the pump or maybe the thermostat (both are prone to having issues).
One way to try and work it out is to drive the car up a hill (they call it `under load`) and see if the temp spikes as the car works harder. This can suggest the pump is failing or not performing properly and can't cope when the car gets hot. It can also mean your thermostat is stuck and restricting water flow. If the car gets hot through `normal` driving it's harder to test.
I had that problem at the start of last year and it was an arse to diagnose. In the end I had the thermostat (and housing - it's plastic and prone to fail) and the water pump (and cam belt - that was due) replaced all at the same time.
When trying to test my car, the water pump wasn't just on or off (much easier to diagnose) - it was intermittent and a pain to work out. One minute under load it was okay, then hot, then okay (the shroud sticks, causes an overheat, then pings open and drops the temp, then sticks again....)
When the pump was changed it was sticking and was replaced with a `revised` version that doesn't have the stupid widget.
So - I'd try to get your coolant levels sorted first before you start chasing anyting else. I had heater matrix, water pump and potential thermostat issues all at the same time. It was sorted once everything was changed but it wasn't much fun trying to work it out.
In terms of your coolant temp - the guage on the dash will say 90 degrees anywhere between about 80 and 98 - it will only actually show signs of overheat when the cars really hot. It's designed not to panic people as the coolant temps fluctuate all the time normally. The best thing to do is get a Carista dongle and an app like inCar Doc that will give you real time figures and you can be a bit more scientific. You can also get an app to monitor your DPF which can be useful.