"Catalyst System Efficiency Below Threshold (Bank 1)"

This is what the error causing the check engine light in my car keeps saying. The pricks at C&C on Western insist that I must pay them to replace my catalytic converter. Meanwhile, everyone else I talk to and everything else I've read (here and elsewhere) lead me to believe it's far more likely one of the oxygen sensors.

So where can I go that won't immediately just insist I need the more expensive fix (cat) without even bothering to check or replace the easier one (sensor), and which, having done so, will replace the thing the cheapest? I'm automotively retarded so suggesting that I buy and install the sensor myself is not helpful.

Thank you, Garage, and please have pity on the ignorant.

3/13/2011 10:04:30 PM

zxappeal could probably do it for you.

I've never met him but he's done work for friends and no one on here has ever said anything bad about him

3/13/2011 10:44:12 PM

It's possible one of the o2 sensors is bad, but normally you would get an additional code for that. There is a good chance it really is a bad cat. If you want a more technical explanation...



In a simple 4 cylinder like that you have an oxygen sensor in front of the converter and a sensor behind. The front sensor should have a different waveform from the rear sensor if the cat is working right.

The converter changes the composition of the exhaust gas, and that's why the rear sensor should read differently than the front. If the sensor waveform is the same between the sensors and the sensor is ok, that means the cat isn't doing it's job. It is not uncommon for some shops to recommend new o2 sensor(s) when they change the cat.

3/13/2011 10:58:39 PM

OK, in that case, is it possible to test the sensor independently in some way? Or is my only option here to replace one, only to find out that the other thing was broken afterwords?

It just seems odd that my cat should be fucked up. The car doesn't have 100,000 miles on it yet -- far, far fewer than my parents Corolla of the same year, for example, which has never had a problem. Not denying that it might well be the converter, of course, but you can understand why I'd want to check less costly possibilities before shelling out $Maryland.

3/14/2011 12:39:22 AM

check your owners manual. often the cat has a really long warranty

3/14/2011 6:40:34 AM

Arghx how often to you see cats actually go bad??

i've replaced 3 o2 sensors and NEVER the actual cat.

3/14/2011 10:20:32 AM

cats normally last relatively long time, but some things will shorten its life....e.g if you overfill the engine oil, lots of short, cold trips etc.

id take the advice from above and check to see if you cat warranty still covers it.

3/14/2011 11:47:02 AM

I think the cat warranty on my 4runner is either 8 or 10 years and 80,000 miles. Your Corolla probably has the same.

I got this exact error message on my truck a few months ago. I reset the code by disconnecting the battery and it hasn't come back. I did pull the O2 sensor off and sand the carbon buildup off of it, but I doubt that did anything to be honest. When it does come back I plan to replace the O2 sensor first. If that doesn't do the trick I'll the catalytic converter, but I'm not paying $1k+ for a Toyota part. Aftermarket cats can be had cheap.

[Edited on March 14, 2011 at 11:57 AM. Reason : s]

3/14/2011 11:56:59 AM

Quote :

"OK, in that case, is it possible to test the sensor independently in some way? Or is my only option here to replace one, only to find out that the other thing was broken afterwords?"

Well there are high-end scantools (mostly the dealer tool) and specific diagnostic procedures to follow. There are specs on how the signal should look. But usually the on-board computer is smart enough to figure out if something is wrong with the o2 sensor. Realistically you would have to take it to a dealer to have techs with the right kind of diagnostic tool. But they would still tell you to get a new cat so that's kind of pointless.

You can replace both o2 sensors and clear the code, hoping it won't come back. You can replace the cat, clear the code and hope nothing else will show up soon after. Or you can replace the cat and the o2 sensors at the same time, which is what some shops will recommend so that they can make more money but also so that you won't come back and complain if something else goes wrong.

For the record, my '99 Corolla which has an earlier version of your Corolla's engine has ~193k on the original o2 sensors and cat. It doesn't surprise me that you are having problems though. We have two Corollas from your generation in my family and I have noticed generally poorer quality such as crappy interior plastics.

Quote :

"Arghx how often to you see cats actually go bad??"

It does happen, especially on older cars and aftermarket cats. I had a friend with a mark IV VR6 Jetta who had the cat go out when it was about 500 miles past warranty. Emissions regulations keep extending the cat warranty so that's one reason why newer cars have longer lasting cats. Go to a muffler shop and much of their business is replacing cats.

3/14/2011 12:06:24 PM

Quote :

"I reset the code by disconnecting the battery and it hasn't come back."

if it's basically a beater and you're trying to save money, I would clear the code and see how long you can push it. I've seen these codes be pretty intermittent

3/14/2011 12:17:14 PM

What arghx said...clear the codes and see how long you can go until it pops up again. The Catch 22 is when it comes time for inspection and your registration renewal.

My car flagged the P0420 code at about 115k miles, after I had replaced the upstream O2 sensor. I cleared it and drove it for a while, and of course it popped up again. Now, it comes on for a while, goes out for a while, etc. When it comes time for inspection, I clear it and drive it for a bit to make sure that all readiness flags are set, then go get it inspected. I'm at 186k now.

Your results may vary, depending on how much oil your engine burns, what kinds of shitty gas you happen to be dumping in it, and your driving habits. The cat stays cleaner and better lit under steady state highway driving.

It's not uncommon for a cat to shit the bed before 60k miles under just the right circumstances. 100k is actually a good lifespan for one. And it's rare to get a generic aftermarket cat that will last much more than 25k miles, though you can buy on with more platinum/rhodium for about 2 to 3 times the cost of a cheaper one.

3/14/2011 12:41:38 PM

Quote :

"clear the codes and see how long you can go until it pops up again. The Catch 22 is when it comes time for inspection and your registration renewal."

Yeah, well, that's the issue. I just got a ticket for expired registration, which I can't fix until I get the car inspected, which I can't do because of the fucking CEL.

And I cleared the codes. Unfortunately the window to get it inspected is narrow -- you have to have driven a certain inexact distance in order to set the readiness flags, but very shortly after that point the light comes back on. I've tried to hit the window once and failed, I can't keep dicking around with it and getting tickets.

But whatever, I'm going to Henry's Mufflers to see what they say, if I gotta replace all of it I'll piss and moan and not be able to do one good goddamn thing about it.

3/14/2011 1:44:42 PM

Just go ahead and get a cheap cat at Henry's. Fuck the sensors for now.

3/14/2011 1:53:25 PM

If the upstream and downstream sensors are the same part numbers you can always swap them and see if the code changes. If the problem sticks with the rear O2 sensor you'll know it's the cat. If it throws a CEL on the front O2 sensor it's probably the sensor itself.

3/15/2011 12:17:07 AM

Quote :

"Just go ahead and get a cheap cat at Henry's."

Ha ha ha ha.

Just got back from Henry's. They called somebody to price the part, saying that they had to order it from a dealer, and then told me that it would cost about $1600 (plus $150 for labor). If that's "cheap" to you then congratulations. To me, it's entirely too close to the value of the car for me to even consider, even if I had money, which I don't.

So I'm still open to suggestions here.

And that includes suggestions of places that will let my car pass inspection for a bribe.

[Edited on March 15, 2011 at 2:20 PM. Reason : `]

3/15/2011 2:18:39 PM

it's not that easy... they have to plug the machine into something

3/15/2011 2:39:39 PM

resistor?

3/15/2011 2:51:29 PM

rear o2 sensor simulator http://www.urdusa.com/index.php?cPath=66_170

3/15/2011 3:09:38 PM

http://www.o2simulator.com/index.php?main_page=product_info&products_id=9:cea2882749ce87d0d4e2d414cfc18ab3

?


^ Looks like we were thinking the same thing...URD was my first choice too, but you may notice that all those parts are for V6 & V8 cars. Not sure what (if any) difference there would be other than the plug.

[Edited on March 15, 2011 at 3:15 PM. Reason : s]

3/15/2011 3:12:50 PM

I'm pretty sure the '03 Corolla has a simple narrowband oxygen sensor in the rear like almost every other car. It might be almost the exact same (or very similar) part as what's used on the V6 and V8 engines. From what I've seen most Japanese cars use Denso o2 sensors.



This one may work. It is plug-and-play which eliminates the chance of installation error. The connector looks similar to what I see on like every Japanese car of this era. http://www.urdusa.com/Electronics-Rear-Sensor-Simulator/c66_170/p1260518914/URD-Rear-O2-Simulator,-2RZ-FE-2.4L-,-3RZ-FE-2.7L/product_info.html

[Edited on March 15, 2011 at 3:27 PM. Reason : pic]

3/15/2011 3:21:42 PM

btw, any muffler shop worth it's weight in scrap tail pipes should be able to offer to replace any 'downstream' catalytic converters with a generic model for <$100+ labor

3/15/2011 4:04:27 PM

Yeah, that really surprises me about Henry's.

Did the OP tell them he wanted the cheapest solution possible? You can get cheap cats for <$70 from Jeg's and Henry's would normally do the replacement pretty cheap from what I've seen.

3/15/2011 4:22:50 PM

The problem could be that it might be a cat that's integral with the exhaust manifold, like a lot of late model Civics, or the cat bolts directly to the manifold, like a lot of Camrys that I've seen.

You can get the direct fit cats for between 275 and 500, I think.

I don't know if it's legally allowable to shove a broomstick through the type of cat above and then weld in a universal downstream...but I'd sure think about it.

3/15/2011 4:29:02 PM

I didn't explicitly say, "I want the cheapest option possible," but when they quoted the price -- it seemed to pain them, too -- I flat out said I couldn't afford that, and they didn't offer any alternative. You'd think they'd rather tell me the cheap option than watch me walk out the door.

3/15/2011 4:29:05 PM

Quote :

"The problem could be that it might be a cat that's integral with the exhaust manifold, like a lot of late model Civics, or the cat bolts directly to the manifold, like a lot of Camrys that I've seen."

this

3/15/2011 5:21:45 PM

I should have clarified more with my above post = 'downstream' meant 'not attached or near the maniflood"

3/15/2011 8:24:17 PM

call up a junkyard. it's a Corolla, I'm sure somebody has one. They will probably still charge you more than you want to pay though.

3/16/2011 12:11:49 AM

I thought the first thing junkyards do is sell factory cats to a recycler for the precious metals.

[Edited on March 16, 2011 at 10:31 AM. Reason : l]

3/16/2011 10:31:22 AM

^ well yeah that is true... I guess the o2 simulator should be the next thing then. I think there's a pretty good chance it will work. And if it doesn't, he can put it on ebay and get some of his money back.

3/16/2011 10:36:54 AM

I'm wondering why broomsticking the monolith, installing a cat immediately downstream, and welding in a second bung wouldn't do the trick. Reckon it would fail visual? I'm not a licensed inspector, so I don't know these things.

3/16/2011 10:49:12 AM

It has been suggested to me that the DMV may grant me an exemption because the price of repairs would be so high relative to the price of the car. Anyone have any experience with this?

3/16/2011 3:45:59 PM

no direct experience, but it is the DMV and you are already overdue for an inspection/registration aren't you? Do you want to be in bureaucratic limbo? I say try the O2 sensor simulator.

3/16/2011 4:06:27 PM

Quote :

"FINALLY got the car registration renewed. This is the process to get a waiver, because the online instructions miss some (big surprise). 1) Visit Inspection Station. Fail the inspection. 2) Carry inspection report to mechanic, have him spend more than $200 in parts and labor trying to fix this. He needs to indicate the code he is trying to fix on the receipt. KEEP RECEIPT OF WORK. 3) Check engine light comes on again after the work. Carry to same inspection station again. Fail the second inspection. 4) Go to the DMV office (this will probably be the office that does your license renewal and driving tests, NOT THE TAG OFFICE. You will meet with an inspector. Have with you BOTH your inspection reports, your worksheet from the mechanic, and registration. He will examine your car, and probably grant a waiver. 5) Go to the inspection station a THIRD time, this time with waiver documentation in hand. Pray that there are no additional codes. I probably spent 8+ hours to get this done. Had the license tag renewal coincided with the inspection sticker, I would have just taken it back to the shop to get it fixed (since I would have 2 months to deal with it). Since it didnt, the state has actually put a car back on the road that fails emissions for one more year. Good job!"

Pg 2 of this thread:
message_topic.aspx?topic=602139&page=1

3/17/2011 10:19:38 AM

Summitracing.com:

Quote :

"MagnaFlow 93200 - MagnaFlow Direct-Fit Catalytic Converters These MagnaFlow Direct-Fit catalytic converters are designed for easy bolt-on installation for the professional installer. Welding, cutting, and tube-bending equipment are not required. $339.01 "

http://www.summitracing.com/parts/MPE-93200/




Me personally, I'd still do the sensor first. That's probably a $70 part (Amazon.com usually has them cheap) and a 15 minute swap. Get a Denso sensor; not a Bosch even if it will save you $20. If you've ever over-filled the car with oil and had it blow past the rings and out the exhaust I'd expect it to be the cat, but all things being equal I agree with sumfoo1. Just my $.02 and I'll be the first to admit that I have nowhere near the experience that some of the folks in this thread have.

Quote :

"Arghx how often to you see cats actually go bad?? i've replaced 3 o2 sensors and NEVER the actual cat."

It's all a guess until you start swapping parts though. I'd rather put in a $70 O2 sensor and find out I was wrong than put on a $350 cat and find out I was wrong.

And again, if the front and rear O2 sensor is the same part which happens all the time on non-California emissions vehicles, you can swap them and see if the code changes. If the code changes to an error on the front sensor rather than the rear sensor then it's probably the O2 sensor.

[Edited on March 17, 2011 at 10:49 AM. Reason : s]

3/17/2011 10:26:03 AM

Never over-filled with oil.

So let's say I buy that direct-fit converter...I still have no idea how to install one. Or the 02 sensors, for that matter.

And I am starting to get real tired of every place I take the car to flat-out refusing to consider the 02 sensors. "The code says it's your cat. You need a new cat." As though the computer, or the thing telling the computer what to think, couldn't possibly have errors.

3/17/2011 12:14:58 PM

the reason why they aren't saying the o2 sensors are bad is because there are no codes for the o2 sensors. Anything is possible, but usually if an o2 sensor is bad there will be a code.

3/17/2011 12:41:56 PM

I don't think junkyards are allowed to resell cats.

But some do

3/17/2011 12:58:48 PM

Quote :

"Anything is possible, but usually if an o2 sensor is bad there will be a code."

See, this is exactly opposed to the consensus of people I talk to who don't stand to make money off me. Really you're the only one in that crowd who swears it's the cat.

As per the recommendation of a family friend I put a cleaning solution in the gas tank and am concurrently seeing about getting the DMV waiver. It has also been suggested that I visit Tilden's on Atlantic, as the owners are supposedly of the same mind as me (that CEL's are a racket). Anyone got experience with him?

3/21/2011 6:03:22 PM

if you are interested in throwing money at the car, i will sell you a fuel magnet to go with that cleaning solution

3/21/2011 7:38:11 PM

I'm sure it's probably stupid, but it was recommended by a trusted family friend, and costs so little that I'm willing to give it a shot while exploring other options. Given that at the moment my other options seem to be:

1) Perform operations myself that I have no idea how to perform
2) Drop two grand on a new cat (which basically amounts to "sell my car and not have one anymore")
3) Try for the waiver (which I'm going to have to wait for a while before I can do anyway),

then I'm willing to drop a couple of bucks on what might well be automotive snake oil.

3/22/2011 12:01:03 AM

Quote :

"See, this is exactly opposed to the consensus of people I talk to who don't stand to make money off me. Really you're the only one in that crowd who swears it's the cat."

"Swear" would be too strong of a word. I have stated that "anything is possible" which could include an exhaust leak for example. I bet at least one of those places would have found an exhaust leak though.

I am saying it is the cat because there are LOTS of things that trigger o2 sensor codes and you don't seem to have gotten any of them. On that style of sensor there is a heater that can go bad which will throw a code. On that style of o2 sensor the waveform is sinusoidal and the computer continuously monitors the frequency and amplitude to determine whether it is working right. It will throw a code if any of that is off. Most of the o2 sensor tests you would do with an expensive scantool are tests that the onboard computer does continously. That's what readiness monitors are.

I'm sorry it could cost so much money to fix properly but like I said I think the newer Corollas aren't as well made as the venerable 90s models. I hope I'm wrong but I'm reasonably confident in my internet diagnosis.

3/22/2011 1:05:14 AM

This site lists a direct-fit cat for $358 http://www.autoanything.com/exhausts-mufflers/77A5366A3705491.aspx?kc=ffsku

I would still try the o2 simulator. It shouldn't be hard to install. You could leave the factory rear o2 sensor installed, plug the simulator in and ziptie it to something. If you can change brake pads or do basic work you should be able to install it.

[Edited on March 22, 2011 at 1:16 AM. Reason : .]

3/22/2011 1:14:08 AM

You can understand, I hope, why I'm reluctant to accept the most expensive option in lieu of those that are both cheaper and more commonly suggested.

Also, as I've said, I'm largely ignorant. I've heard "direct-fit cat" bandied about, but I am ignorant. I have no idea what distinguishes that from any other cat, or if it will work with my car, or even if I had one, how to install it (or whether any shop would install it for me). I will, however, look into it. Thanks.

3/22/2011 1:18:04 AM

sounds like grumpy's gonna do what he wants to do anyway, right?


[/thread]



P.S.

direct fit = bolts into existing exhaust system with no modification required. application specific.

universal = must be fitted/welded into the exhaust system, and the original usually has to be cut out with a saw. these are usually made to function with a certain range of engine displacement & vehicle weights based on the converter media type and design/size/tubing size of the converter case.

3/22/2011 8:14:27 AM

Quote :

"If you can change brake pads or do basic work you should be able to install it. "

Yeah...about that...

Although I suppose I would be willing to pay a wolfwebber to put it in or come show me how. Without hands-on instruction I'm just worried about making things even worse.

---

So with the direct fit...what do you mean by "application specific?"

3/22/2011 9:38:58 AM

Direct Fit means it's made for your car...As in, you unbolt the old one and bolt this one in place. No welding or tube bending required.

Exhaust bolts can be a bitch though. The heat cycling tends to stick them in place pretty well. I've probably had to cut off or break off as many as I've been able to get off with a wrench.

Any mechanic or quite a few wolfwebbers should be able to install it for you. I don't have the time to maintain my own stuff right now, so I wouldn't be able to help.

[Edited on March 22, 2011 at 9:59 AM. Reason : s]

3/22/2011 9:58:21 AM

application specific = the part is made specifically for your year, make, model, engine, etc. of car, specifically.

3/22/2011 9:59:32 AM

OK, thanks. That may well end up being the way I have to go. If so I'll probably see if any wolfwebbers want to make a buck doing it.

3/22/2011 10:16:45 AM