Epic revival here........
Right. I took the car into Vauxhall dealers in July. They said they'd had a few issues with this on some insignia's and that they would change the unit.
When i got the car back, it seemed fine. I thought it odd that i didn't receive any paperwork. But then with everything electronic and with it being a warranty job i didn't think much of it.
Few months later the light comes back on, so i book it in again and had a service whilst i was at it.
Came back ok.
Just atfer xmas (warranty ran out 21st dec 13) light comes on again.
The car is back in today for another 'fix'.
They just rang me to say they can't any issue and it would cost £78 to diagnose. I'm like, even though the car is out of warranty surely you are duty bound to fix what you've failed to fix on 2 previous occasions when it WAS in warranty?
2n visit to fix it they told me the cap was lose (basically accusing me) I didn't even know where the cap was!
Spoke to manager and he says that out of the 3 or 4 visits to their garage this year there is absolutely no record of any coolant issue being looked at!!! WTH?!

Seriously? He also said that even if there was, once the warranty is out of date then i have to pay for it. Even if they didn't fix it 1st or 2nd time round.
If that's the case then them 'losing' any record they have of me bringing the car in twice previously for this issue is irrelevant now as the warranty has ended.
So, anyone any idea at all what might be the issue? Faulty sensor? Leak somewhere? I resent (and can't afford) £78 to have the issue diagnosed, then pay to have it fixed.
Peeved and gutted about this.
Any advice?