I think that the totally arbitrary limits on CO levels, Lambda values etc are totally unacceptable in MOT tests. Who decided on these ridiculous limits? I'll bet that they had no professional qualifications in car maintenance. My car scraped through two years ago with a Lambda reading of
1.03 (on the upper limit) after the fast-fix outfit (I suspect fraudulently) charged me for a new Lambda sensor at £65. Last year, the reading was 1.001 at a garage I found I could finally trust (unfortunately now out of business). What is the accuracy of their analysers and how often are they calibrated? This really amounts to a licence to print money for the MOT stations.I would question the accuracy of these tests, and also the proficiency of the operators. What training have they received, and if they have, are these people capable of understanding the intricacies of the modern car.
I actually dread my next MOT test, when I will be subjected to the incompetence and perhaps the greed of the operator. Perhaps even a new catalyser might be recommended next time, in order to make a profit for these crooks. Unfortunately, the only answer seems to be to buy new car and part exchange it before 3 years or alternatively to buy a 25 year old Merc and sod the emissions tests and possibly also the road tax.
Terry D.