MonsterS - thanks very much I really appreciate it. I’ve seen things like suspension bushes etc but I have no experience of it and wouldn't want to do anything to damage the vehicle or make it unsafe.
Had this warning light on my 2005 hybrid, and sometimes the engine would cut out and I had to wait 10 mins for it to cool down. Found out that there are 2 radiators and cooling systems - one for the engine and one for the inverter. The problem was solved by having the water pump on the inverter cooling system replaced.