My brothers escort gti failed an mot on emissions.
I know the cat is only a year old and suspected the lambda.
When i tested it it was giving very high readings (i expected this) but they was so high I thought maybe they was out of range and the ecu was ignoring them.
Got another lambda of a car and bodged the wiring up a bit but this hasnt helped the problem. After a good run this is also giving very high readings indicating that it hasnt helped lean out the mixture at all.

Any ideas on what to check next?
He changed the throttle body and the unit that bolts on the side of it. Not sure if that is the ISCV or throttle poistion sensor.

The MAF sensor is doing something as when unplugged the car runs very lumpy. I know this dosent mean its definately working right but just trying to save him a few quid before he sends it to a garage.

any thoughts would be good, and if there is a way of adjusting the mixture even if its just to get it through the MOT it would help and at least keep him on the road