Is it an MOT failure?
It comes on randomly now and again since the exhaust system was changed. I've always been able to turn it off using the OBD2 but I'm having a problem this time. The OBD2 seems to be having trouble communicating with the car. No fault codes are showing and the MIL is showing as "off".It will be from 1st April if it isn't already.
Do you know why it is on?
Can it be cleared by a reset?
Is there anyone near with a scanner, I'd happly do it, it only takes a few seconds but I don't think you are in north West Sussex.