RX8 catalytic converter questions

I have a 2009 RX8. The check engine light illuminated on saturday. Shortly after that I noticed that the engine seemed down on power at full throttle and high rpm. Without a load the engine accelerates normally. At partial throttle it also feels fine. I suspected the catalytic converter was begining to melt and plug. I drove it over to the local autozone to have the code read. The codes came back as oxygen sensor and catalytic converter. The converter is warrantied for 96 months.

This is the first car that I have owned that has a warranty. My first thought was to cut the cat out and replace it with a "test" pipe. I have the tools and ability to do this in the shop. However it is covered so I am leaning toward having it replaced at a dealership.

I have a few questions. Does anyone here have experience with the Mazda dealership in Brighton MI? On a warranty job like this does Mazda provide the part and I pay for labor, exhaust hangers etc? or is the entire job covered by Mazda?

Any advice is appreciated.

I had the cat replaced on my S1. Assuming your diagnostic is correct they will cover everything required. If you are not correct you may have to pay for some of their time to diagnose the issue. If my recollection correct, I believe the code is P0420, but as you noted there are multiple possible causes. If you check the deeper OBD2 data you can gain confidence in your diagnosis (if you're not already).

P0420 is the cat code yes, and it will (8-10 times) be covered under warranty as well so just go in and have it done.

Rotarys do NOT like cats or were designed for them, even with all the improvements in the S2 it is still running not only rich but burning a good bit of oil both by design for safety of the engine and this will always mean an early death for the cats.

With my 2010 I have the cat on for long trips (have an un-resonated racing beat test pipe and even with the stock cat back it's a good bit louder) and having to go to emissions testing. It is only 45min to switch them out and has a nice mid range bump in power, only draw back is you will have a CEL on for (you guessed it!) P0420 but it does not effect power or MPG, you also get rid of a heap of weight from the stock cat.

Thank you Snrub and JtspellS . That is the code that was coming up.

Since the cat is covered and if you live close to Detroit, get it replaced since the air is more polluted there.

And since this is grm you should ask to keep the old cat and sell it to recyclers. It's gotta be worth near $100. It's huge.

cat probs even on the S2? dang...

I would get them to warranty the cat then once they got all the new hardware on with the new replace it with a test pipe on your own time and save the cat for time of re-sale or re-purpose. Its a win win win if you ask me. Your engine will thank you without it, the hippies might not but oh well.

For what it's worth, my friend that used to race an RX8 in T2 used to replace his cats several times a year. Yes, they failed that quickly and dropped the hp.

It's possible that the cat is being burned up due to a bad coil pack, which would also explain the lower power. I would consider replacing them if the car is getting up there on miles.

Dealer will cover the entire cost of the cat and labor - had it done on our 2006 RX8 about a year ago. Was free under federally-mandated warranty for emissions equipment.

Coils, plugs, and wires first. Then get cat replaced, otherwise it will go bad quickly again. I am going through plugs at 15k miles, but that is due to tracking the car. I noticed a difference when I changed them. Coils I changed at 35k miles. I am currently running a test pipe due to the fact that the car is 90% track only these days, and I also run some Idemitsu Pre-mix with the fuel. Stock cat still looked good at 35k miles. Also check to make sure that all the intake flappers are working (3 of them I think). clubrx8 also has the factory manuals for a 2009 online. I bought some off of ebay. PM me and I can send you the ones I have downloaded.

I thank all of you for the advice. I have changed my plugs regularly, at 54,000 miles I am preparing to install the 3rd set. The coils and wires are original. Should I replace them with aftermarket or OEM pieces?

pilotbraden wrote: I thank all of you for the advice. I have changed my plugs regularly, at 54,000 miles I am preparing to install the 3rd set. The coils and wires are original. Should I replace them with aftermarket or OEM pieces?

Replace with OEM. BHR is the only other alternative and I've heard mixed things on them.

I used the latest Rev "C" coils from Mazda. Mazmart had pretty good prices. I also got Mazdatrix wires.

Yeah I agree on using OEM coils. I have the BHR harness and Yukon coils in our car now and it's no better than OEM. I would have gotten Mazda coils with hindsight.

I picked up the car today. It has a new catylytic converter and oxygen sensor. It was covered under the warranty. It runs strong again. The mechanic advised that I should put new plug wires and plugs on the car. That will be the project for tomorrow..

@54k for coils on an RX of any generation is far beyond the normal realm, do all 3 (coils,wires,plugs) if you can afford it if not start with those coils and OEM is always the best bet here.

Quick RX8 Cat q: What should be the ballpark for replacing the cat on an RX-8?

In reply to JtspellS:

Coils and wires are ordered. I always have a set of new plugs in the glove department.

In reply to scardeal:

Price wise I'm not too sure Tbh, but it does only take 45min to change it out and install the new one.

In reply to JtspellS: Is it in the $200, $700, $1000 or $2000 ballpark?

Quick look from atkins rotary is $1300, you can dig around and probably find it for cheaper.

Das link