Coolant temp exceeding 90 degrees intermittent problem

[vag12]

As above my car randomly starts going past 90 degrees to about 110 degs, would the cause be waterpump? I done a vcds scan came up with p2185 - engine coolant temp sensor on radiotor outlet, could it just be a sensor issue or waterpump?

[martin@gti.co.uk]

Are both radiator hoses warm? Bottom and top?

[vag12]

Yes the are

[martin@gti.co.uk]

It will be the sensor then. Replace when engine is cold. And it will need a top up after warm up. G13 or similiar.

[Degudodger]

Does this occur after driving at mixed speeds or after, say a sustained speed on the motorway?

[vag12]

So it definately won't be the waterpump then? Because this problem has been there for over a month and it only really starts to go past 90 after about 1-2 hours of driving, also worth mentioning if I run the car heaters while the temp has exceeded it will crawl back to 90 again, or in engine is switched off and turned back on again it drops slowly.
The symptom of water pump failure would show loss in coolant etc?

[timwills17]

I'd say if no steam is coming from the engine bay it is nothing to do with the engine more to do to sensor giving a faulty reading. Replace the sensor...shouldn't be much only. I agree with martin

[martin@gti.co.uk]

It wont be the waterpump as there is a flow. Both hoses are warm. You could get the infrared temp gun at maplins and check coolant temp to comfirm reading with vcds. Might be thermostat if reading correctly. But the fault code points out the sender unit.

[Chris01]

I reckon that this is one of the first things you checked but mine used to have a coolant leak. One of the plastic joints that distribute the coolant had a small leak, which finally resulted in lower coolant level and a warning light in the dash. If it is a leak, watch for white dried up fluid in the engine, it should be easy to spot.