c30 2litre auto
 

fitted new brake light switch now " engine system service required" message comes on and off is this a faulty switch.

any ideas.?

Do you have any kind of diagnostic tool (VIDA would be best obviously)? The car will tell you what it thinks is wrong and you can work from there....

The problem was had not put the brake light switch in the fixing properly the local garage I use for m.o,t,s found the problem with there computer read out came up faulty brake light switch, took the switch off and put back on, problem solved. Why does the car put an error code like that.

it recognises a fault in the braking circuit, subsequently it flags a warning.