Engine light on 2011 defender 110

Engine light is on checked on computer it said Mac sensor replaced this light still on got the computer to turn it off again stayed off all day next morning it's on again got it switched off again and it stayed off all day the next morning it's on again
This has now been on for the last two months it starts and runs fine
Does this vehicle have a cold start sensor could this be the problem and if so where is it
Thanks. George

I think it was Mac it might be Mac anyway it was something to do with the airflow