P0420 code pop up. rpms drop from 8 to 2 as it almost stalls. What do you think?

Question

P0420 code pop up. RPMs drop from 8 to 2 as it almost stalls, strong smell, unusual exhaust smell? What do you think?

Answer 1

The P0420 code is for a bad catalytic converter on bank1. Depending on the vehicle I would inspect the converter. Since the vehicle is trying to stall, it's very possible the converter is broken up inside and plugging up. This is where I would start.