It may depend on the vehicle you drive so you should consult your vehicle handbook for the precise meaning of this warning light, but if you drive a diesel the emission warning light may be indicating that the diesel particulate filter (DPF) needs regeneration. You can activate this by taking a journey of approximately 20 minutes or more with the engine running at above 2000 rpm.

If this does not cause the light to go out you may wish to have a diagnostic check from a local independent garage.