At it's last MOT at 160,000m, the lambda reading for my 1999 1.8 Vectra, was 1.029, that is just OK, top limit is 1.030. The year before it was 0.997. From this, I reckon that the next MOT in 4 months may be a failure on this. Are these difficult to replace, and is the reading a sign of something else going wrong? I know little about these. The reason I ask, is that the clutch now needs replacing, about £500, and I am wondering if it's worthwhile. I should add, the car has been reliable the past 9 years, no other obvious faults, drives well, and gives good mpg. However, I do have a slight feeling I could be wasting money, and may be better to scrap it. Any advice would be much appreciated, thank you.