Thanks Gareth, wise words. I’ll contact the seller and let him know. He ‘seemed’ a genuine guy.
Not longer after posted the question I read that not tightening the fuel cap until it clicks a few times can be a common cause of the engine light. Do that, wait 2-3 days, see if the light is still on was the advice. As such I did so, and edited my question to query another problem (recently bought 13 year old car = several newly discovered niggles). But you appear to have nipped in with an answered before the update. Thank you though!
I’ll let you know the sellers answer and if the fuel cap solves it. And if you can shed any light on the latest issue please do share!
Thank you!