It's a brand new oe sensor, but the old one worked fine going to a Surrey meet then all of a sudden it just jumped 40° then it was a bit hit and miss, hence me buying a new one. The thing is I've kettle tested the sensor and it works fine so it's not the wiring or the gauge. But I will check the voltage, just need a tester now
I'm going to have to replace the pump or at least split it apart to see what's going on. It's something small and annoying because I drove back to kent from Santa pod at 30° air temps with the gauge showing 120° and I didn't have any overheating problems.