Jake Jones

I just fixed some big holes in my exhaust and replaced my valve cover gasket. Since then, I am getting some errors:
P0420 Catalyst System Bank 1: Efficiency below threshold
and
P0130 Oxygen (lambda) sensor B1S1 Malfunction in circuit

I don't think they are related to the repairs, but it's not boosting well, actually feels like it looses power at +3500 rpm instead of gaining.

I apologize if this is covered somewhere else, not really wanting to start replacing the CAT, O2 sensors, or turbo before I am sure I know what I should fix.

Thanks

Jake Jones

AMB motor, Quattro

Teknic

If I had to guess, I'd say you need a new cat. How many miles on the car and when was the cat last replaced?