Engine management light on after fitting new snsor

Hi, this car is now driving me crackers, first issue fan not kicking in and only running at 2 bars,i have replaced top sensor and thermostat ,the new thermostat solved the cool running and now running at 3 bars however the fan was not kicking in until it reached the red mark ,but at least I knew the fan was working, today I unplugged the cylinder side sensor but had to replace as I didn't have a socket to fit, when I put it back on and started the car it self diagnosed but then went straight to red and the fan was on constantly ,I pulled up and disconnected the fan as it was running while parked up ,when I came back and sterted the car the engine management light came on ,I re- connected the fan and the management light stayed on , I changed the cylinder sensor and that took the temp back to normal running at 3 bars but I still have my engine light on and the car is running fine,any ideas as to why and what I can do.Thanks

I still have my engine light on and the car is running fine,any ideas as to why and what I can do.Thanks

You can see what has caused the MIL by using lexia, but I suspect the MIL will extinguish after a number of engine starts where the fault is cleared. My advice, leave it for a week and drive normally, if the MIL is still on, then dig out lexia.