Comments on: P0420 Code (Symptoms, Causes, and How to Fix)

By: Kb

Kb — Sun, 11 Sep 2022 21:19:27 +0000

In reply to Sean. P0420 is not often a root cause. Replacing the cat should be the last resort. It's the symptom of something not right upstream (running rich or lean).

By: Sean

Sean — Mon, 02 May 2022 16:14:23 +0000

In reply to Jim Libert. It's probably not the computer. In fact, I would guess the computer is doing a good job of helping you narrow down the problem. I wonder if it's the catalytic converter. Catalytic converter issues are common root causes of the P0420 code.

By: Jim Libert

Jim Libert — Fri, 29 Apr 2022 17:50:05 +0000

I changed the o2 sensors 2008 Chevy Avalanche. Check engine light comes up every 2 weeks. sometimes a bit of rough idle at 500 RPM other times runs great. Spend $ $ 450.00 at Midas they told me it was operating fine and ran some cleaner through the engine. Light came back less than a week later. computers on cars suck.

By: Sean

Sean — Mon, 09 Aug 2021 16:23:10 +0000

In reply to Ronald Lofton.

You might try cleaning the catalytic converter first. Check out this article: https://cartreatments.com/how-to-clean-catalytic-converter/

By: Ronald Lofton

Ronald Lofton — Sat, 07 Aug 2021 19:18:49 +0000

I have a p0420 code on my 2018 chev equinox lt 1.5 tubrocharge. But mechanic saying it might be my o2 senor but I change and code still come up. Should I just change coverter?

By: woody

woody — Sat, 01 Aug 2020 08:26:27 +0000

Very helpful really. I have one in at the moment with p0420, more to look at than just the cat… Meow….