2014 silverado 1500 bad catalytic converter Code P0420

Logan S · December 31, 2020

Hi guys! One more for you. I'm Logan. I have a 2014 Chev Silverado 1500 Z71 the check engine light came on a couple weeks back P0420. I took it to an exhaust shop that I trust and they told me both cats would need to be replaced. They said my truck has new cats on it, that aren't cheap one's, but unless it's factory it will throw the code. There experience has been that the only cats that won't throw a code are the OEM one's.

They would have rather sold me an aftermarket exhaust which I would have been happy to pay for. Are there aftermarket cats that I can buy so I don't have to pay $1200 from the dealer? I did find one used set for $600 on craigslist.

Thanks!

CamGTP · December 31, 2020

They are likely right. Aftermarket cats don't work as well as the OEM and that is partly why the cost is so high and because GM will charge that much just because they want a big profit margin on parts.

A work around is to space the rear o2 sensors out of the exhaust a little bit. It's a pretty common thing to do with aftermarket cats or to just stop a cat code from coming up.

Even with a P0420 code it doesn't mean that the cat converter itself is going to become plugged up and cause an issue. It's just not working up the standards of the rear o2 sensor/emissions level. I would space the sensor out some before I spent $1,200 on new cats. We always called it the spark plug non-fouler trick because they are the same thread size as an o2 sensors and with two of those non foulers along with a drill it makes a spacer. Google it if you want.

Or if I owned the truck I'd just tune the codes out because I have a tuner.

flyingfool · December 31, 2020

possibility OEM cats are designed to operate at very high temps and not get damaged. aftermarket cats use cheap materials that wont handle the heat most likely. there is a PID on these trucks that gives you the Cat temperature , find out what your temp is at.. I'll look up mine and see if its similar or not even close to a working system

TJay74 · December 31, 2020

Just a FYI the OEM cats are covered under the Federal coverage for 8yrs or 80k or 100k miles.

yTry · April 26, 2023

On 12/30/2020 at 11:17 PM, Logan S said:

Hi guys! One more for you. I'm Logan. I have a 2014 Chev Silverado 1500 Z71 the check engine light came on a couple weeks back P0420. I took it to an exhaust shop that I trust and they told me both cats would need to be replaced. They said my truck has new cats on it, that aren't cheap one's, but unless it's factory it will throw the code. There experience has been that the only cats that won't throw a code are the OEM one's.

They would have rather sold me an aftermarket exhaust which I would have been happy to pay for. Are there aftermarket cats that I can buy so I don't have to pay $1200 from the dealer? I did find one used set for $600 on craigslist.

Thanks!

Hey Logan, I’m having the same issues. Did you resolve this. If so, how?