Apparently posting an ad on the local used car website scared the poor thing into working as I noticed the coolant temperature wasn't going up anymore when standing still and sure enough the radiator fan now works! (It never worked before except on a lexia fan test.) I then cleared the codes with my cheap blue generic obd2 bluetooth adapter and surprisingly enough the damn check engine light has not returned. It has now been 2 days over 100km and 10+ engine on/off cycles and it has not come back so I assume the issue whatever the hell it was has somehow gone away??
This means that I am obviously not going to sell it because what would be the point if it now works fine again but if anyone else finds this thread looking to solve the same issue then I truly have no idea what caused it or what solved it.
Oh and a completely unrelated thing - did anyone know that the rear seat bottom flips down into the foot area and makes room for the rear seat to fold completely flat? I had no idea and just assumed that the seats only fold down about 2/3 of the way.