https://www.obd-codes.com/p0420

Exhaust leaks? Look at the list of causes and see if any apply to your exhaust

 

No exhaust leaks. The O2 sensors are about 18 months old. No problems until the new system was put in and about 500-700 miles put on it. You tube suggests spark plug non fouler extensions. Is that my next project? I can imagine a new converter is already dirty with no engine changes. Do people put 2 of them on? or just the back one?

 

https://www.chevyhhr.net/forums/2-2l...20-code-58413/

My adventure with O2 extender

it is always a possibility to contact the catalytic converter supplier and see about their warranty replacement.

 

I'll get it up on the ramps today. There may be a possibility of the manifold to the cat flange bolts loose as I read to torque them to only 20 ft lbs. Seemed a little on the low side to me. But I'll start there. I'll have the extenders with me as well, they are fairly inexpensive and in stock at AutoZone. Simple enough to a least give it a try. . Keep ya posted and thanks for the reply.

 

Will these do the trick if needed? 18 mm

https://www.autozone.com/ignition-tu...009/730544_0_0

 

Should but might need to open them up to 1/2 inch hole so the sensor fits into it. I installed one of these longer ones
2Pcs O2 Sensor Spacer, M18*1.5 Spark Plug Non Fouler Catalytic Converter Cleaner Check Engine Light Fix Extension 45mm Length (Silver) (Type D) https://a.co/d/ga2awYV

 

Checked system for leaks, all is good. Added the adapter and drilled it out. So far about 65 miles since and no code. Hopefully it's a cure.

 

Fingers crossed!

 

Almost a month and still running good and no codes.

 

Ok, I can uncross my fingers, oh that hurts, such a cramp!