Never heard that before - definitely a deluded old wife tale. It takes a fair bit to knock out a cat. I remember an HT lead failing on our old VW Passat 2.0GL with at least six figures on the clock when on hols in France - we had to drive for many miles limping along with just three cylinders, but it didn't affect the next MoT emissions test.
Not so sure. The wasted spark coil pack failed on my old Octavia 1.4 16v a few years ago effectively dropping the engine to two cylinders. I was about 10 miles from home and decided to carry on driving. Drove surprisingly well considering - engine management somehow maintained tickover speed however top speed was only just over 30mph.
Fast forward to the next MOT and it failed on emissions. Replacement of Cat restored health. Did the coil pack failure cause the failure - not sure.
Same car at 120000 miles (approx 60k later) and it went again near home. I stopped fairly quickly and there was a very hot smell (which may have been the coil!!)- when repaired car passed next MOT just fine.
As the coil pack was cheap and a very easy fix decided to carry a spare!
Edited by Big John on 02/03/2021 at 20:04
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