My Ford car failed its MOT, due to emissions, so we changed the catalytic converter and replaced the sensor - the management light kept coming on prior to this and the mechanic said the code reading was for emissions.... so now after a service and having made the changes the management light is still coming on and the mechanic has cleared the codes again, saying the codes are referring to emissions,.... and I must book the car in AGAIN for further investigation. Surely I have done everything now to rectify the issue of the engine management light coming on.... what else can this be....?