16’ Chevy Malibu limited LT
Hey i having trouble figuring out why my car is saying “ catalytic efficiency threshold bank 1” is showing up on engine code. I switched out the bank 1 O2 sensor Upstream and im Replacing the O2 bank sensor 2 downstream tomorrow. But i don’t know if i should replace the cat itself because it turns the code off every now and then but i put cataclean in the system so far twice. But never had this problem until they rebuilt my transmission and had to disconnect my cat from my muffler now i need help.
im Replacing the O2 bank sensor 2 downstream tomorrow
Does the sensor test as bad?
i don’t know if i should replace the cat itself ... had to disconnect my cat from my muffler
You did not state the code number but presumably it is P0420. There are quite a few things that can cause that code, including exhaust leaks.
https://www.walkerexhaust.com/support/tech-tips/diagnosing-catalytic-converter-p0420-code.html
https://www.way.com/blog/p0420-code-what-it-is-and-how-to-fix-it/
https://www.obd-codes.com/p0420
@chucktobias Not sure but i figured i just change them to new now since i replaced one. But i will definitely check the link you gave me. And get back to you.