Clogged catalytic converter 10k miles on 2016 silverado

Timmyboy188 · September 3, 2016

I took my truck in to have a rear end squeaking noise looked at, and they somehow found a soft code and rooted the issue back to a clogged catalytic converter. They replaced the converter under warranty, but I have concern as to why this could happen in the first place. I Have run e85, 87, 89 and 91 in those 10k miles to determine the best gas to run, maybe that has something to do with it?

Any ideas? I worry this could be the result of a bigger issue...

andyhaug · September 3, 2016

Here are a couple of possibilities. Not sure how I feel about the second one, seems like dirt going through the engine would be bad for everything.

Premature Catalytic Converter Failure

October 22, 2014

If the catalytic converter has failed or DTC P0420 (Catalyst System Low Efficiency) or P0430 (Catalyst System Low Efficiency Bank 2) is set on some 2015 and prior GM cars and gasoline-powered mid-size trucks, light-duty trucks and heavy-duty trucks, inspect for a poor crimp at circuit terminal on the engine bank with the condition.

Inspect the ground for possible corrosion or damage at the ground terminal ring, fasteners and grounding surfaces. (Fig. 12, 13) If no corrosion or damage is found, tighten the ground bolt to the proper torque specification. (Fig. 14)

Fig 12

Fig 13

Fig 14

– Thanks to Richard Renshaw

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Air Filter Box Seal Leak

April 25, 2016

On some 2014-2016 Corvette, Silverado, Sierra; 2015-2016 Escalade models, Yukon models; and 2016 CTS and Camaro equipped with a V8 engine (RPOs LT1, LT4, L83, L86, LV1, LV3), the MIL may be illuminated and DTCs P0420 (Catalyst System Low Efficiency) and P0430 (Catalyst System Low Efficiency Bank 2) may be set. These conditions may be caused by excessive dirt/debris entering the air filter box and bypassing the seal of the air filter, causing damage to the H02 sensor element (Fig. 15) and blocking the catalytic converter. (Fig. 16)

Fig. 15

Fig. 16

Do not replace any parts for these conditions until the air filter housing has been validated to be completely sealed.

Inspect the air housing cover for any missing tabs or fasteners. Also remove the air filter housing cover and inspect the seal around the filter as well as the air filter sealing surface for signs of not contacting the air filter seal. (Fig. 17)

Fig. 17

In addition, look for dirt/debris in the air filter housing cover bypassing the air filter. (Fig. 18)

If dirt/debris is bypassing the air filter due to a faulty seal, replace the air filter. If the air filter housing is not properly sealing, refer to the appropriate Service Information for additional diagnostic procedures.

Fig. 18

silveradosid · September 3, 2016

good info thanks andy

mbaker7667 · September 6, 2016

I am heading back to the dealer tomorrow for this issue. I first went to them for a different issue and after they diagnosed they said my Mass Airflow sensor was bad. after they replaced it, I got another engine light. I went back and they said it is for the catalytic converter. They said there is no reason for a 2015 to have an issue with the Cat. so they are going to call GM and see what they suggest. the truck has 22k miles on it and it has been running fine up until now. the initial reason I brought it in was because it died while driving to work. the engine shut off and I lost all power steering and it took about 30 min of trying to turn over before it finally did. after which it sounded like I had no exhaust and the lights where flickering. I hope no one else has had these issues but if you have can you share what the outcome was?

thanks KS for your help and thoughts.

bkeith5050 · October 2, 2020

On 9/6/2016 at 12:12 AM, mbaker7667 said:

I am heading back to the dealer tomorrow for this issue. I first went to them for a different issue and after they diagnosed they said my Mass Airflow sensor was bad. after they replaced it, I got another engine light. I went back and they said it is for the catalytic converter. They said there is no reason for a 2015 to have an issue with the Cat. so they are going to call GM and see what they suggest. the truck has 22k miles on it and it has been running fine up until now. the initial reason I brought it in was because it died while driving to work. the engine shut off and I lost all power steering and it took about 30 min of trying to turn over before it finally did. after which it sounded like I had no exhaust and the lights where flickering. I hope no one else has had these issues but if you have can you share what the outcome was?

thanks KS for your help and thoughts.

I came across this thread looking for O2 sensor info, but for anyone that has had issues mentioned above with your truck dies while driving down the road and EVERYTHING shuts off, it's the ground cable going to your battery is the issue. GM didn't make a recall for this and just issued a new part number that can be replaced. I had this issue that happened to me about 5 times and could never figure it out and neither could the shop I took it too. I found on another forum a couple of years ago when it happened this info I'm sharing right now. I had my shop custom make a new ground cable out of welding cable so it's heavy duty and guaranteed to never fail, which is what I recommend to those experiencing that issue. I wouldn't recommend buying the new replacement part, just have a custom cable made. I also had a 2014 silverado too.