Hopefully i can help..
Just to clarify which warning light are you refering too?
Has the engine overheated before hand or any issues with engine temp..ie:- overheating etc?
Has anything been already checked/replaced upto now?
Any unusual noises from the engine when this occurrs..missfiring / lack of power etc?
being the new owner I have ased the question to the former owner they say it has not overheated
the warning light is not very big and looks like a portcullis gate
I have not had any checks done
engine runs fine
Hii there thanks for your reply..
Ok..ideally first off if you havent done so already is inspect the coolant level. "at cold" see what its sitting at..if a little low then top it up to required level max and then try that..also too see what its sitting at when HOT but do not open the cap only ever open the cap when cold..and monitor what the level is at that..it sounds very much like either coolant level issue..if it comes to it maybe opt for coolant system flush/thermostat change or a coolant temp sensor a diagnostic test would maybe see that and verify especially so even if it the square zig zag warning signifiying an electrical fault/or possibily even a level sensor if fitted to the expansion tank..all that has to be ruled out..if you 100% sure the engine isnt overheating then as above would be one of the areas to inspect..I do hope this helps