When Im driving along the temp gauge sits under the 1st marker (about 3/4 of the way up between cold and the 1st mark) and the heater doesnt work very well. If Im sat in traffic for a few minutes itll heat up and the gauge will move to dead on the middle marker but as soon as I start moving again the temp gauge bombs.

Is the thermostat stuck open? The garage said they dont think theres anything wrong with it but I want a 2nd opinion cos I think thats bull.

sounds like the stat is stuck open to me, had it in a car before, never warms up

The thermostat is usually easy to remove and inspect.
Another possibillity is what you are low on coolant/water.

whats your mpg like? if the stat is stuck open it should be terrible.

if its easy enough to remove on those, then take it out and stick it in a pan of water and boil it, see if it works.

Sounds like thats what the problem is to me too. Cheap to replace also if it is My car heats up in a few mins and Im getting maybe 1-2mpg more since having mine replaced.

I read somewhere theyre £90 but hopefully the warranty will cover it...

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Oh yeah youve got the Mini now, BMW parts are expensive but £90 for a thermo?

Quote from: DEViANCEwhats your mpg like? if the stat is stuck open it should be terrible.

if its easy enough to remove on those, then take it out and stick it in a pan of water and boil it, see if it works.

Was going to say that but a visual inspection would tell if it is stuck open and a boil will tell if it opens and when, if combined with a thermometer

sdp did you check the water/coolant level ?

Yeah the coolant level is spot on.

£90 for a stat is a joke, more like £9