my emission light has come on?

it means your car has a fault, if you are not mechanical minded a good garage will read a fault code and replace the offending part.
However first have a look, is it using a lot of water ? if so it needs to be taken to the garage immediately as the head gasket may be going, if the water is fine, its usually just a simple part like the oxygen sensor and should cost around £100 to fix

mark readman
March 2010

It could be that your egr valve is dirty and needs cleaning, it could also be a dirty air filter or your cat converter, what model and what type of fuel. Post again

bob
March 2010