Damaged Catalytic Converter?

Factual Questions
1

So, my check engine light went on and an analysis said that it was my rear oxygen sensor. Aha, says I, now that I live in a place with a garage, this is exactly the simple kind of repair I can do. Little did I know.

It turns out the forwards O2 sensor is accessible from above after removing the heat shield on the exhaust manifold, not to hard, but the rear one seems to be located on the top of the catalytic converter in a very inaccessible place. I think I would have to remove the converter to get it out. Not what I was looking for. I have the Haynes repair manual for my car (2003 Ford Focus SVT), but though they mention the existence of the sensor on some models, they do not list a good way of getting at it. Ugh says I.

While I was down there, though, I noticed something about the converter itself. The thing goes through a 90 degree bend and this section has a metal flange on each side where the metal for the top and bottom parts are welded together. One side looks like a standard weld, but the other side looks like it is missing the weld and there is collected black soot all over the flange, as if it had been leaking exhaust gases.

So, my question is, is that normal? Here is a picture of the good side, and here is a picture of the bad side. If this is an actual problem, then I think it is most likely due to poor initial manufacture, and I should then be able to get it replaced on warranty. If that is the case I can get them to stick the new O2 sensor on at the same time and save me a hell of a lot of effort. They would charge me several hundred dollars to stick the $50 part on normally.

So, what do you think? Oh, and sorry about the image quality, but the camera isn’t very good and since I just have the car on ramps I can’t really back up far enough to get a good shot.

2

Catalytic convertors have something like 150K mile warranty independent of the car, IIRC. I can’t tell if there’s anything wrong with it from your pics, but if there is, unless the dealer can prove that you deliberately screwed it up, they’ve got to fix it under warranty. Getting them to swap out the air sensor at that time, should be doable, but I won’t hazard a guess as to what they’ll charge you for that. Rick should be a long with a good answer soon.

3

Thanks! I looked more closely at it and it appears that the seem was originally welded but the weld line cracked for half its length on that side. I have never tried this before, but can you generally get them to install a part you supply, rather than having to pay their inflated (double!) price? If they have to replace the the converter and use the sensor I supply, then there would literally be zero extra work involved.

I just read only about the additional required warranty with environmental systems like that. One place said around 80K miles, so either way I should be good. I am interested in doing a bit of my own work on the vehicle, but this would be a large project for me to start with.

4

If they have to replace the Cat, won’t they have to replace the sensor too, anyway?

5

I would have thought they would reuse the existing sensor, but perhaps I am wrong. Do new catalytic converters generally come with oxygen sensors?

6

::: sigh:::
How many miles on the car? Depending on where you live, you converter will either be covered for 50,000 or 70,000 miles. Read your owner’s manual and the warranty booklet for exact details. If and I do repeat if your car is was sold as a California specification PZEV car then it would have a 150,000 mile warranty on all emission components. Again RTFM. or call Ford consumer relations phone number with your VIN and ask them.

Is your converter bad? Beats me. From the pictures I have no clue. Focus is a good thing, you should try it sometime. :smiley:

Will they put in my O2 sensor when they replace the cat? There seems to be a serious misconception here. When the ECM says part A is bad that is because either the reading from part A is zero, battery voltage, or is implausible. The reason the reading is zero could be because the wire to part A is shorted to ground. One reason for the reading to be 12V is because the wire to part a is shorted to a 12V source. The reading is implausible could be because part B is bad, giving part A a bad signal. The code for part A could be the result.
Write this down, it may be important later:
Just because a code says a particular part is bad, that does not mean that replacing the part will fix the car.
Now if the converter is covered, most likely, so would the O2 sensor. RTFM.
but what if the O2 sensor is not covered, would they install my sensor? Not if the shop had three brain cells to rub together.
There are a couple of scenarios here:

  1. Your part fixes the car, everyone goes away happy, birds sing, and flower bloom. Not bloody likely. That asshole Murphy is standing right behind me to make sure this does not happen. Either you brought me the wrong part, or it is bad out of the box. You get pissed when I want money to do the job over again.
  2. Your part does not fix the car. You get pissed at me, forgetting entirely that YOU diagnosed this bad boy, and you can talk to the guy responsible tomorrow when you shave. He will be right in front of you. You get pissed when I want money to accurately and correctly diagnose the car.
  3. Your cheap part fails in a couple of months. You claim that I must have put it in wrong. nope, you bought a piece of shit.
    Sorry I only install quality parts that I can trust. I cannot trust parts you supply.
7

O2 sensor? Just recently here in the U.K., there was a batch of bad fuel which damaged the O2 sensors on thousands of cars.

8

Rick, thanks for all of the help. The car is out of general warranty, but select emissions devices, including the catalytic converter, have an 8 year 80K mile warranty.

I wish I could have gotten better pictures, but as I mentioned the poor quality camera could not focus on something so close, as the car was only up on a pair of ramps. I included them anyway so that people would understand what I meant by “flange”.

The shop told me that it was the oxygen sensor and quoted me a repair cost. It is possible that the only analysis they did was pull the error code, but I would hope that if they quoted me a repair cost and did not mention other likely problems (which could be much more costly) that they would have a reasonable guess that that was what was actually wrong. Perhaps I am being too optimistic.

I cannot tell if the O2 sensor is covered based on the manual. It lists “onboard emissions diagnostic devices”, which, to my untrained ear, sounds a lot like an O2 sensor, but may not be. The question I had was that if they had to replace the cat, do they naturally replace the sensor, or do they take the old sensors and reuse them?

You are, of course, right about the use of an owner supplied part. That was silly of me to think they would. Thanks for breaking it to me gently.:slight_smile:

Ah, if I remove the last “s” I find through Google that “onboard emissions diagnostic device” means “…any device installed for the purpose of storing or processing emissions related diagnostic information, but not including any parts or other systems which it monitors except specified major emissions control components.” So they are systems that interpret signals from devices, not the devices measuring what is going on. Seems that they mean the OBDII system. That answers whether the sensor itself is covered, but as you mentioned, it may not be the sensor itself that is the problem.

You obviously have a great deal of experience with this, and I obviously don’t, though I do want to learn. I had been considering purchasing an pc-based OBDII scanner and wonder if you could make a recommendation. Part of an attempt to better familiarize myself with my vehicle and how it operates, as well as perhaps identify problems early on. I have several friends who would also be interested in splitting the cost. The ones I had looked at on-line seems to go for around $200 and an extra $150 for the Ford specific codes.

Also, for a novice like myself, is it worth investing in the Helm repair manual for my vehicle over the Haynes one? Even I can tell that the Haynes isn’t very good, but it was all that was available at the auto supply stores I visited. I have heard good things about the Helm manuals, but think it might be overkill for me. Is there anything else out there you know of off hand? Thanks for taking the time to think my problem over.

9

In my reading about these things, they seem to be very sensitive to fuel problems. The front one is supposed to be the more sensitive one, though, and the back one (which is a bit more protected by being behind the catalytic converter) is the one that failed for me. Thanks though.

10

Oh, I forgot to mention, I did not that there was no visible damage to the sensor itself or its wiring, and the connector was firmly attached. I guess that doesn’t mean much as the sensor is supposed to very susceptible to bumps.

11

Flight there are several flavors of emission warranties. What is covered can and will vary from year to year, as the law changes. Coverage will also vary with where the car was first sold. (California warranty for example is different that most other states. However there are some states that are adopting California rules.
bottom line, get out your owner’s manual, and the warranty book and read what is covered.
I know for example that for some years, here in California, on the extended part of the emission warranty only parts that had an installed price of $700 or more were covered. I believe this has changed, but the only way to be sure is to read the book for your car. If you are missing the book, call Ford consumer affairs dept.

About the converter, I have been trying to figure out what effect an air leak on the back side of the converter would have on emissions and the rear sensor. There is a slight chance that an air leak could cause the computer to think the rear sensor is bad, it would depend on just where the leak is in comparison to where the sensor is mounted, and the logic used in the ECM. I am afraid that I don’t know either for your car.

I would hope the shop did some diagnosis, but since I wasn’t there watching, I have no clue. here in California, if the shop sold you the sensor, and the exact same code reappeared you would have a great case to take to the Bureau of Auto Repair. There is an excellent chance you would get your money back. Your Mileage (and state) May (and probably will) Vary

As far as the OBD scanner goes, I don’t have a clue, as I have always used the factory tools. You don’t even want to know what these cost. Word of warning, look very closely at what systems they cover. They may not be able to access all the various systems in the car.

As far as the books go, Haynes is a good basic manual. I am not familiar with the Helm book. If you are buying a scan tool try to find a manual that covers the various Diagnostic Trouble Codes for at least the engine. For ford fuel injection, Amazon has a number of books that cover Ford FI systems.

BTW if I came off a little snarky in my last post I would like to apologize. I had a really rough day yesterday. Normally I am not that big an ahole in a car thread.

12

If the catalytic converter is not performing properly, it’s eligible for warranty replacement. A broken or missing bracket weld might be considered a non-critical flaw, not eligible for warranty. If there actually is a leak in the converter, that may be eligible. I think you’d really need a converter evaluation by a dealer to determine if it’s covered.

It’s not that front oxygen sensors are more sensitive than rear ones, but that they are reading more fluctuation in exhaust oxygen content. If the catalytic converter is doing its job, then there is less fluctuation for the rear one to respond to. Often the functional design of front and rear O2 sensors is identical (wiring connector portion is usually not).

Dropping the exhaust enough for access to the sensor might not be as hard as it first appears. It probably would be necessary to disconnect the header pipe flange from the manifold, but then possibly only one or two hangers to get to the sensor.

The converters I’ve seen do not come with sensors installed. You would reuse the old one, or separately buy a new one.

Sometimes those sensors are badly rusted in, and need stout tools, even special ones, and a lot of gorilla oomph to break loose. Other times they come out without too much trouble.

I’ve never heard of O2 sensors being susceptible to bumps. Every car in the world goes over all kinds of bumps every day, and the sensors last for tens of thousands of miles.

13

Thanks, that helps.

Mine would be the former. The only appropriate tool my local auto parts store had was an offset socket, but even that does not allow access. I have seen specialty wrenches available online, and that would likely be the only way to get the thing off without removing the catalytic converter. Hopefully this won’t be an issue and I will be able to get the shop to take care of the whole thing.

The package the new one came in is full of all kinds of dire warnings about being extremely careful with it. I guess it is more impacts than bumps though.

Rick, I checked the manual, that is where I came up with the “onboard emissions diagnostic device” verbage, and it seems that the cat is definitely covered and the sensor is probably not. I will take your advice to call them up for a final word.

Thanks for the analysis of the problem. I am mostly concerned with if “cracked weld and leaking gases” = “new converter”, and it seems like people are saying probably but not definitely. This gives me some more information for when I speak with the dealer. I have had problems with them before and do not entirely trust them, so want as much info as possible. I will only be going back to them for emissions work as that is only thing that is still under warranty. I just don’t want to find out that there is supposed to be a gap there or that black soot often collects around the weld line after taking it in. I know those sound pretty silly, but I want to make sure there isn’t something blatantly obvious to someone who knows cars that I am just unaware of.

Thanks for the info on Haynes. Perhaps I just got unlucky with the sections I have looked at. They seem to have a basic template which they modify a little for each model car they cover. I have seen a few sections incorrectly referenced and indexed and they missed the part I was concerned with, but if that is just a fluke I will stick with it for now.

The OBDII scanner I was considering is AutoEnginuity. It costs another $150 for the Ford expansion, but if it doesn’t cover something, than I am unaware of it.

Now worries about the snark, I was being stupid.

14

Update:
Just to thank people for their help and let them know how it turned out. I took it to the dealer who was unable to find a problem with the cat.

I told them to look harder. They still didn’t find a problem.

They asked me to show them while it was on the lift. We had to turn the engine on and poke and prod and they eventually said, “Huh, look at that, guess it is cracked.” Sheesh.

So, I have them replace the cat (fully covered by warranty) and the O2 sensor, which they insisted was a separate problem (not covered). The sensor cost about $110, but there was no labor charge since there was literally no extra work to be done than with just changing the cat out. Now it runs fine.

I had considered having them just do the cat and see if that fixed the problem, but if I was wrong then the labor for the O2 replacement would have been significant, so I played it safe.

Thanks for the help with this everyone.

15

Sounds like you’ve paid for your membership here for many years just by inspecting the cat on your own and pointing out the crack to the dealer.

Regarding O2 sensors and bumps - what they’re referring to is not bumping the naked business end of the sensor before it’s installed. Once it’s screwed in, it should withstand pretty much any bumps in the road that don’t break the car’s frame.

16

Glad it worked out for you.