Our 2000 2.4GDI Spacewagon has geerally been reliable but with 80K on the clock it has just failed the MOT because the emissions were too high (10% CO). A local mechanic ran diagnostics and cleared a fault code and reset the ECU this resulted in the CO coming within range (1%) but the Lambda dissapeared off the scale, at too low to read! We have both been scratching our heads and trying to figure out what is wrong, could this be down to the infamous throttlebody soot?

the cat is coked up