MOT failure emissions, high lambda

[Marks DTM Calib]

No SAI on 2.2.

Given the values seen for coolant, the fact the O2s are switching, MAF is plausible I would say its getting air into the exhaust or the tester was up the swanny (I fractured pipe on the analyser would result in O2 being sucked in).

Clearly the CAT etc is all good, HCs good, so the engine is actually in fine fettle yet there is excess O2 in the system

[terry paget]

Original testing station could not do me a retest because the proprietor, a sole trader, is unwell, and been absent for some time, so the department of transport has ruled that no more tests can be carried out there until further notice. Boring. So I took it somewhere else, and it failed again, on emissions. But this time lambda was fine 1.006, 0.995, but CO was O.58% and 0.36%.

So it looks like I need a new cat after all.

[terry paget]

Rejoice, rejoice! MOT finally passed, all emissions low and lambda 1.002. My thanks to all for advice.

I had a spare genuine Vx cat section RobG sold me some while ago which I fitted. Genuine Vx cat sections weigh 10kilos, aftermarket ones weigh 6 kilos. Need I say more.

I suspect the second lambda sensor was also faulty, because having swopped it with the sensor off Ben's 2.2 it switched rich/lean just like the front sensor, while the suspect sensor, now on Ben's car, reads lean continuously.