Thanks for the response. I have cleaned the fuel injectors using Redex and changed the Lambda probe. Unfortunately, the car still failed the emissions test today. I have arranged for a diagnostic test on 24/4/03 but would be grateful for any advice as to what else could explain the high CO and Lamda readings that are reported. I should add that the Hydrocarbon readings were well within the acceptable range and the car does not have any other symptoms which could help the diagnosis. The CAT was replaced last year...could it be faulty?...there are no strange noises from the CAT or any other signs such as blockage.