My check engine light came on last week randomly while I was on the highway and the code was P0420: Catalytic Efficiency Not Supported..

I know it's not the converter. I've maintained my car and engine constantly. But I'm trying to clear the code so I can test and see if it really is the converter or if it's the sensor that's messing up. Because those are two different fixes with two very different fix prices!! Anybody know how to clear the codes? Because apparently it's "illegal" for a auto parts shop to do it. They'll check it for free...but they can't clear it. Lol fml

 

Unplug the negative battery terminal for 5 mins or buy your self a obd2 scanner and erase it.

 

Clearing the code as above can be done with an inexpensive OBDII reader, but if it comes back, you're going to have to address it. I vaguely recall getting this code in my car years ago- I swapped out both O2 sensors, and the code never returned. Catalytic convertors generally don't fail, but O2 sensors do- if the code comes back after clearing it, I'd recommend changing both O2 sensors and use Honda branded sensors vs universal type.

 

Okay I'll give that a try and check it out.

Yeah that's what my guy was telling me. That once I cleared the code that if it came back on instantly that it was the sensor, or if it came back on after a day or so that it was the converter. Or maybe the other way around, I don't recall sadly ha! And what's the difference in the sensor productions?

 

^^ You could probably get away with an aftermarket part, but for the emissions system, I'd go OEM (that's just one opinion however).