P0420 Code. Where to start?
Senior Member
Joined: Mar 2015
Posts: 253
Likes: 14
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The membership includes the FREE* 2 Day shipping.
*with the amazon prime purchase.
5 Year Member
Joined: Aug 2011
Posts: 292
Likes: 7
From: Mansfield,Ohio
My F-150 (2005, 4.6L XLT, 150k miles) had a check engine for a couple months now. I've erased it and it has kept coming back. P0420. I've done some reading. Apparently it's the catalytic converter, O2 sensors, or bad gas. I'm not sure if the cats are to blame as the previous owner swapped the stock exhaust for a dual pipe Flowmaster (40 classic I believe) setup. Ever since my latest fuel up I've been getting the worst gas mileage, but that code has come up before so I can rule out bad gas. I've replaced the fuel filter recently as well. Should I replace the O2 sensors? Or take it to a mechanic to check for cat problems? Thanks.
little late in the game to be asking.what exactly was the problem with the code0420 on your truck? im having the same exact issue.im trying to narrow it down to the main problematic source.your advice could do me wonders.
5 Year Member
Joined: Aug 2011
Posts: 292
Likes: 7
From: Mansfield,Ohio
letting everyone know mine was a clogged injector.fuel injector cleaner from autozone did the trick.after dumping it in half a tank of gas,few mins later while driving engine went away and hasnt been back on since.