Was getting a rattling at idle. My stock cat caused similar issue years ago and I replaced with a high flow model. This one is shot as well. The question was asked of me about my o2 sensors and if I had replaced either of them, which I have not. Is it reasonable to expect a cel if there was a need to replace the sensors?

 

First off what kind of title is that?? I was expecting some major LOL moment when i opened up the thread!

Somethings amiss, your cat shouldn't have been "bricked" like that if everything was working well. If things weren't working well there should have been a CEL thrown. Those o2 sensors are there to monitor the exhaust and if the cat is busted out theres no way it's working right and you should be getting CELs.

Are you the original owner? Maybe a previous owner had a midpipe and had someone suppress the CEL for it and then threw the old busted cat back on so they could sell the midpipe for cash when you bought it.

 

Yes bro' it's been mine since Oct 2003. Attachment is the o2 sensor I just replaced. It took a hit at somepoint, it's bent. A wire was also nicked leading to the plug. Not sure why there was no cel before now. But it threw a code day one driving with the new cat. Cleared it and put in the sensor. We'll see. . .

 

O2 sensor when fail, usually will give u a cel, but sometimes it might not, just giving cel a steady reading when its not, so no ecu (stuck in some value) but it has already failed.

lace it every 50 k just to be safe, not expensive anyway

 

Hi guys,
Please excuse me for butting in.
I was told the 420 code could signify bad 02 sensor.
Is there an 02 specific code?

 

All the codes are here -
https://www.rx8club.com/series-i-tec...n-guide-26291/

Codes 130 to 140, 420 to 430, 2090 to 2100, 2190 to 2200, 2270, etc., etc., check 'em out......

 

Thank you very much.
That's a lot of codes.

 

Some JDM CEL is not listed on the USDM spec RX-8.

 

does replacing the front sensor matter if u dont have a cat?

 

Yes, it's what tells the ecu what the f/a mixture is. Without it, the ecu has to guess.
Without a cat, the rear one isn't necessary. That is just there to check catalyst efficiency.