2001 Avensis SW P0420

[ToyAven1.6]

Hello to all

Finally my girl is out of the paint shop she is all beatifful and shiniiiiiiing!!!

But now two tthings appear. 

THe code P0420 (Catalyst system Efficiiency Bellow Threshold (Bank 1) 

SHe was stop for a long time, is it the Kat dirty or the sensor if its the sensor can you point me on the right direction please?

There is also a clunk on the back on bumps I have replaced the drop links but no joy!!

Some times the speedometer stops working then after a wile cames alive again!!! Any advice on what to do?!

Many thanks to all 

[ToyAven1.6]

Anyone!!!