Aftermarket vs OEM catalytic converters

wdfifteen · wdfifteen's Garage

Does anyone have any experience using aftermarket cats? My Tundra needs the left cat. Price from local Toyota dealer is $12xx. Price from on-line OEM supplier is $9xx. NAPA has a Walker brand cat for about $300. That's a lot of $$$ less. I live in Ohio, so I don't have to pass CARB tests. Is the $300 cat really bad? If so, in what way?

Aragorn · 04-22-2014, 05:49 AM

Catalytic Converters (Both) Are Bad... - Tacoma World Forums

Over $1,200 for a consumable part?

As long as the aftermarket part meets specs and has a warranty I would go with the cheaper part.

herr_oberst · 05:58 AM

I put a NAPA/Walker on my Toyota P/U. Bolted right up with no issues, passed DEQ a couple of weeks ago. Good enough for me.

Toyota has really gotten proud of their replacement parts of late.

VincentVega · 04-22-2014, 06:04 AM

I used the various versions from ******** on a few cars with no issues. I did however have a problem with one of the cheaper generic versions on a Celica a few years ago. I think it makes sense to spend the $$ on one of the direct fit model specific versions instead of cobbling one together.

onewhippedpuppy · 04-22-2014, 06:19 AM

From what I've read, if you stick with a name brand aftermarket cat (Wagner, Magnaflow, etc) you will be just fine. The ultra cheap no-name ones can be trouble. Remember that Toyota buys the cats from someone too, there's not a factory somewhere making cats to a higher standard for just Toyota.

widebody911 · widebody911's Garage

A couple years ago I bottomed out my E46 M3 and destroyed the exhaust; new cats were ~$4000 and when I asked the shop for the old one they told me "uh, we had to turn it in as a core."

A buddy of mine has a 550 Maranello and blew out a cat. A new one was $10k (there are two). He bought a used one for $2500.

IROC · IROC's Garage

Internet legend says that non-Toyota cats are bad about throwing P0420 codes. There's some logic behind the story, but it's more about the threshhold that triggers the P0420 code than the quality of the cat, IMHO.

Is your cat "bad" or are you just having P0420 code issues?

wdfifteen · wdfifteen's Garage

In my case the cat itself it probably OK. But it's part of a welded assembly and the pipe coming out of it is rusted in two.

john70t · 04-22-2014, 07:54 AM

Quote:

Originally Posted by widebody911

A couple years ago I bottomed out my E46 M3 and destroyed the exhaust; new cats were ~$4000 and when I asked the shop for the old one they told me "uh, we had to turn it in as a core."

Must declare before work starts, technically.
Write it on the work order.

Consumer's Guide To Automotive Repair In California
"If you want any of the parts returned to you, be sure to say so when the technician gives you the estimate."

aschen · 04-22-2014, 07:55 AM

if I lived in a place with no emissions testing I would consider just replacing it with pipe...you can put a piece of tape over the CEL.

Replacing it with an aftermarket cat is the responsible thing to do though. Who cares if it throws the occasional code.

OEM cats are always heinously expensive, Im not 100% sure why.

aschen · 04-22-2014, 07:56 AM

Quote:

Originally Posted by john70t

Must declare before work starts, technically.
Write it on the work order.

Consumer's Guide To Automotive Repair In California
"If you want any of the parts returned to you, be sure to say so when the technician gives you the estimate."

I think you get 20 bux or so to recycle a cat right? The tech probaly bough a 12 pack of good beer with it.

1990C4S · 04-22-2014, 08:14 AM

Quote:

Originally Posted by aschen

if I lived in a place with no emissions testing I would consider just replacing it with pipe...you can put a piece of tape over the CEL.

Replacing it with an aftermarket cat is the responsible thing to do though. Who cares if it throws the occasional code.

OEM cats are always heinously expensive, Im not 100% sure why.

If you have a flashing CEL you want to know about it.

john70t · 04-22-2014, 08:15 AM

Quote:

Originally Posted by aschen

if I lived in a place with no emissions testing I would consider just replacing it with pipe...you can put a piece of tape over the CEL.

Some mftrs use a 'safe/limp mode' when certain sensors aren't working (or data is out of whack), IIRC.
OBDII is pretty smart.
This may lead to other engine problems.

aschen · 04-22-2014, 08:25 AM

my subaru had an intermittent check engine light for 70k miles, for an auxiliary air injection valve. This is a valve that opens to reduce emissions by 1% during cold starts.

I finally had to reflash the firmware to permanently delete the code, so I could pass inspection.

OBD II is mostly about emissions. I was a being a bit facetious about tape over the cel, however I wouldn't be a bit concerned about an occasional cat inefficiency code from an installed aftermarket cat.

Tobra · Tobra's Garage

Always buy quality aftermarket cat, unless you live in California. If I were ever in the position that I needed a new cat, I would got get one installed in Reno. California mandates that all cats be replaced with factory parts.

wdfifteen · wdfifteen's Garage

Quote:

Originally Posted by aschen

if I lived in a place with no emissions testing I would consider just replacing it with pipe...you can put a piece of tape over the CEL.

^^
I've been doing this for 6 months. I plug the scanner in every now and then to see if there's anything but the P0420 code ("catalytic converter not functioning efficiently) showing.
A straight pipe would be OK with me, but:
1. I'm not sure if the signal from the downstream O2 detector has anything to do with engine management or is just there to monitor the cat.
2. I don't know of a place that can make a replacement straight pipe that would do it, as it is illegal.

Aragorn · 04-22-2014, 10:45 AM

Quote:

Originally Posted by wdfifteen

^^
I've been doing this for 6 months. I plug the scanner in every now and then to see if there's anything but the P0420 code ("catalytic converter not functioning efficiently) showing.
A straight pipe would be OK with me, but:
1. I'm not sure if the signal from the downstream O2 detector has anything to do with engine management or is just there to monitor the cat.
2. I don't know of a place that can make a replacement straight pipe that would do it, as it is illegal.

google "ohio law on emission tampering" and a fact sheet comes up which explains tampering

wdfifteen · wdfifteen's Garage

Quote:

Originally Posted by Aragorn

google "ohio law on emission tampering" and a fact sheet comes up which explains tampering

I haven't googled it, but I'm 100% sure replacing a cat with a straight pipe is illegal in Ohio.

Aragorn · 04-22-2014, 11:00 AM

Quote:

Originally Posted by wdfifteen

I haven't googled it, but I'm 100% sure replacing a cat with a straight pipe is illegal in Ohio.

I was agreeing with you. I just listed looking up the fact sheet to show all the things that Ohio's EPA says are tampering with the emission system; such hollowing out the cat, using a straight pipe or removing an air pump or air pump belt.

aschen · 04-22-2014, 11:21 AM

yes of course it is illegal. In fact replacing it with a quality aftermarket cat might be illegal as well. I think it depends on the area. Like I said the responsible middle ground is the aftermarket cat.

Lots of things car enthusiasts do are technically for "off road use only".

The air injection in my subaru has been illegally disabled. I am not going to spend a whole saturday and 700$ in parts to light off the cat 30 seconds earlier. If you want to turn me in to the EPA, send me a pm and Ill give you my info so they can make the arrest.