Hi,

I have a 2004 FL1 TD4 with only 115 000 miles.
I drive it mostly in the city, very little highway, motorway, autobahn ...

There is a strong smell when the engine is cold ( outside of the car ), almost nothing but still present when the engine is hot.

Should the cat converter be changed in the car life ?
Should I wait it fail the MOT, before replacing it ?

They normally only get changed if the car fails on emissions or they leak exhaust gas if physically damaged.