Code p0420?

2014 GMC TERRAIN

91,000 MILES • 2.4L • 4 CYL • 2WD • AUTOMATIC

BLBLAZER701

MEMBER
6 POSTS

Getting a p0420 code. Is there any way for a DIY'er to determine if it's the actual catalytic converter? And I've tried to look up the cost for the part and kind of all over the place. Can you tell me what an OEM replacement part would cost?

Jan 3, 2025 at 1:20 PM

STRAILER

✓ASE Certified Mechanic
54,832 POSTS

With no other codes chances are the catalytic converter is bad but, if you have a scanner the long and short fuel trims should be within ±10%.

The P0420 code on your 2014 GMC Terrain indicates a Catalyst System Efficiency Below Threshold (Bank 1).

I have seen catalytic cleaners work pretty well, but to do the job right you must remove the unit and have it chemically cleaned, which should be cheaper. Please go over this guide as well:

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Here is the cost:

Catalytic Converter Front California 22794837 $850.00
Federal 20910567 $1025.00

Here is what it looks like. Check out the images (below). Let us know what you find.

Image (Click to enlarge)

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Jan 3, 2025 at 6:24 PM

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