P0420 and tapping!

[stefan-west1]

Hi all I replace the cat on a 1.0 seat arosa s and since then it's started to make a loud tapping/ticking noise that matches the engine revs. It kinda sounds like a diesel I will try to get a video later.



Also the reason I changed the cat is because I got the code p0420 I think is. Basically saying the efficiency of the cat in bank 1 is below the threshold. I changed the cat at the front of the engine that comes off the manifold but still getting the code after an erase?



Any help is much appreciated

 

[stefan-west1]

Anyone?

 

[ianswebb]

Could be a shot lambda probe or 02 sensor as they are sometimes knows... you may have a model with 2 of these sensors.. one pre cat and one post cat. If this is the case,it is more than likely that the post cat sensor has failed.

Ian