Code p0420 came came up on my OBD reader?

120,567 MILES • 6.2L • 4WD • AUTOMATIC
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DURRAN DAVIS
  • MEMBER
  • 3 POSTS
The code p420 came came up on my OBD reader so I took it to a exhaust shop and it fall to cold came up for them to and the first thing I said change out the cash so I'll go to another shop same thing as long as I was trying to explain that I wanted I want to get him a little see what's wrong make sure you know something else they all said to change the cash out so how can I get up how do you get a true evaluation Dolly telling me to change the cash out p
Oct 17, 2026 at 5:16 PM
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STRAILER
  • ✓Experienced Mechanic
  • 55,682 POSTS
P0420 means the computer detected low catalytic-converter efficiency on Bank 1. This is common when he cats needs to be replaced, here is a video to show you how.

https://youtu.be/CORe9JyrexI?si=OolSO1qCEie0b62d

Clear the codes once completed.
Oct 18, 2026 at 8:39 AM
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