Mini service....?

[sparky35uk]

Just completed a 'mini service' today on my X308 (2002); oil & filter change and a new air filter. On completion the engine management light was on? I reset this via my OBD code reader, but just wondered why and did the car 'know' i'd been working on it?
Has anyone else come across this?

[Tame Technician]

YOU unpluged something with the ignition on. Air Mass meter when you did the air filter??

[sparky35uk]

Ah, that was it....yes I did unplug it to change the air filter!
Thanks Tame.