2016 1.5L diesel cat/dpf failure

[ADEYT17]

My Qashqai is in the garage after losing power and not accelerating. The garage changed the O2 sensor which didn't fix the problem. They then said the manifold was sooted up so cleaned it and the car was ok for a few miles before the fault returned. After further investigation they have said the top of the cat/dpf which is one unit was melted. They said the faulty sensor could of caused over fueling and caused the damage. The garage is saying im looking at over £1000 for the cat/dpf unit but cannot guarantee it will fix the fault. The garage has had the car for three weeks so the labour cost is going to be already huge.

[lewisbryant]

Have you seen the melted dpf? Pictures would be ideal so that we can agree its melted or not, might be just guessing and the service advisor or desk person who has no mechanical knowledge whatsoever is just making up some bull to justify them changing it.

[Weasel]

Have to agree with, Lewis...your garage has had 2 guesses so far and neither was correct all costing you money ( unless they did it for free ), maybe their third guess about the melted cat/dpf might also be incorrect, like Lewis says ask to see the melted part.

[ADEYT17]

The cat and dpf filter is one unit, the garage has cut the unit into three sections. I visited the garage and had a look and inside was completely blocked and damaged. The garage has unblocked it best they could and there is airflow through now. The plan is to weld the sections back together, refit and see if its cured the problem. The worry is it may not work and ill have huge labour charges and a broken car, or it is cured but for how long.

[calnorth]

Wouldn't it be the case that it's illegal to interfere/alter a DPF unit ? To cut it up and then weld it back seems a weird thing to do. Why not a new one?