Question

On my 1999 Volkswagen Passat, where is it located? I got the engine code P0420 Threshold Bank 1

Answer 1

HI there,

This is the catalytic converter between the 2 O2 sensors on the car. The Code you indicated is a P0420 which means the converter isn't doing it's job anymore.

Answer 2

P0420 VOLKSWAGEN Code - Catalyst System Efficiency Below Threshold Bank 1

Read more: https://www.autocodes.com/p0420_volkswagen.html