engine warning light come on whille engine is running

check to find out if you have a cylinder head problem, or plus and wires

Your OBD has detected a fault somewhere, could be many many things. It needs a scan to see what the fault is, may be something minor, Check your gas cap, and most parts houses will do a free OBD scan

the engine was pressure tested all was fine

OK that's good but there are lots of sensors, solenoids, electronics that can light up the CEL or yellow engine symbol. Good compression is important but there is much more to it than that