the original problem was the flange connecting to the flexi part of the exhaust rusting to pieces and coming apart.

Its a ford fiesta flight 1.3 early 2002 endura engine.

There were no warning lights previous to the swap. I was careful with the sensors and swapping them to make sure they were not knocked or dropped etc

It was an aftermarket part, comes with a 3 year guarantee. Gaskets were replaced as were the bolts.