SofaKing_Lou

I just bought a 2007 RX8 6spd last Saturday and today the code showed up on my way home.
Can someone guide me to a current topic about it because I only found posts from 2008.

ouimetnick

P0420 Catalyst System Efficiency Below Threshold.

You need a new catalytic converter. Do not continue to drive with a bad catalytic converter as you can cause engine damage, or in extreme cases, set the car on fire.

It's also possible that the cat was previously gutted and the code was cleared. A gutted catalytic converter is basically a straight pipe, so you could ignore the P0420.

My advice would be pull the catalytic converter off, and gut it of it hasn't already been done, or replace the cat.

SofaKing_Lou

Ive drove the car for 200 miles since buying it and nothing popped up if they did reset it. I have another car to drive until I can get it figured out.
Thanks
What about it just being 02 sensors?

iTs Ghastly

P0420 is a different code than a failed 02 sensor iirc, couldn't tell you the code for that off the top of my head, google can tell u that. You can test the catalytic converter without pulling it off, but generally speaking, if it isn't already gutted, your cat is done in. There are 3 viable options for you at this point.

1. Pull your catalytic converter and gut it. This will lessen restriction in your exhaust, potentially offering you minimal hp gains, as well as removing an area of potential danger. Driving with a clogged cat = Dead engine. Just ask Williard. This will mean you will have a Check Engine Light illuminated reading P0420, and will continue to, but it will eliminate the risk to your vehicle. This can cause issues with emissions testing if that is something you have to deal with in your area

2. Replace your catalytic converter with an OEM Replacement from Mazda. These are very expensive ( in the 1000usd range). Your general catalytic converter from autozone or what-have-you will melt under our vehicles heat. while they do fit, they will likely fail within 100miles of installation . some last longer, but point is, it isn't made to withstand our heat and you will be doing this way more often than you want to if you take the cheap route.

BHR and HJS are both options for you as far as aftermarket goes. IIRC BHR makes a catted midpipe or a cat for their midpipe, and HJS is claimed to be able to withstand tracking temps, so they should be sufficient for what you need. Outside of these two options I know of know that would be cheaper than a OEM and would withstand our temps.

3. Replace your catalytic converter with a cheapy from autozone, and gut your old cat. Run your old cat between emissions, and when you need to pass a sniffer test when your inspections/emission run out, swap your shiny new autozone one on for the test. Its more work intensive, but covers you for your emissions and you don't have to worry about a clogged cat.

SofaKing_Lou

Thank you for the info.
I don't have to worry about emissions testing.
Damn this sucks, I just got the car and you are saying not to drive it until I gut the cat?
After I gut the cat I'll be alright to drive, right.

iTs Ghastly

any of the above solutions will render your car safe to drive. but until you do something with it, i would highly suggest not driving it. I dont know if you have done this yet or not, but it would also be wise to have a compression test done, for one, to see the health of the engine, for two, to give you an idea just how much money you really want to put into this vehicle.

Compression tests for this vehicle are different from your traditional piston engine compression tests , so you will have to go to a mazda dealership or rotary specialist to have this completed

If you don't know what I'm talking about, here is a post i made a little while back on another thread reguarding somebody else buying a used rx8 without a compression test, as well as refer you to the following two links. The following links will have a wealth of information that you will need in your venture with owning an rx8

nything like
Rotor 1: 80psi
Rotor2: 86psi

or
Rotor 1: healthy
Rotor 2: healthy

or anything with just one number per rotor or no numbers at all, you did not get anything meaningful from your test.
ideally you should get something that looks like

Rotor 1: 110psi, 108psi, 110psi
Rotor 2: 110psi, 110psi, 108psi
RPM: 250
then adjusted to your altitude at area of testing.

measurements can be in other units but you want 3 numbers per rotor and your RPM with your results

with your results after normalization you can verify good compression via this chart
http://www.rx8help.com/img/compression_chart.png



https://www.rx8club.com/new-member-f...causes-249529/

https://www.rx8club.com/new-member-f...t-here-202454/

https://www.rx8club.com/new-member-f...ot-8-a-202548/

SofaKing_Lou

Thank you. I will do compression test next week.
The car is at the shop because I couldn't make it up there to pick it up in time.
Thanks for the info.

Alex Blazin

Ya I got one of those dual res mid pipe so he said the light would come on and it's that code... It's just that the oxygen sensors are now different from the front to rear? And it stinks like crazy rich burning gas now? Is that just fine?