codes description

Question

Pep Boys gave me these codes, what do they mean and how do I fix them? P0300, P0430. for a Toyota 4 runner 2004

Answer 1

Hi there,

P0300 is a multiple cylinder misfire code. This can be caused by several things, usually bad ignition coils, wires or spark plugs.

P0420 is for the bank 1 catalytic converter working below efficiency. This actually could be caused by the misfire problem if the misfires are on bank 1. I would start by doing a good tune up and clearing the codes to see which return.