Honda Civic 2002 DX Catalytic Converter/Exhaust Manifold


This is my situation: About 3 months ago, I took my car to a repair shop for an unrelated problem and was told that my exhaust manifold was cracked. In Honda Civics (or at least for my year), the exhaust manifold and catalytic converter are one integrated part, and must be replaced that way. Fine, I shelled out the $900, and had it replaced (No longer under warranty through Honda, over 80,000 miles).

At the end of last month (Oct.), I took the car for inspection at the dealer and passed inspection (after replaced bushings) and emissions testing. About a week and a half later, I noticed a squealing/shrieking noise coming from the front of the car while idling/driving at low speeds after the engine had warmed up. I took it to Honda, was initially diagnosed as loose belts, but returned with the same problem the next business day. After a test drive with the mechanic, they diagnosed it as the catalytic converter gone bad (breaking up from the inside, shields missing).

I am about to take it back to the mechanic that replaced the part (the part is under warranty) and have it fixed. Any ideas about what might have caused the CC to go bad so quickly, as it is brand new? The car is fine otherwise and performs adequately, though I am afraid to drive it at this point. I read that if stuff gets lodged in your exhaust from the CC, it can cause a power failure/stall. Any insight/suggestions is/are appreciated.


Things that can cause the substrate in catalytic converter to break apart are, an engine that’s missing, or thermal shock like running through deep water while the converter is very hot. Things that can cause the substrate to melt are an engine that’s running rich or using a higher octane fuel in an engine that doesn’t require it.

But what I don’t understand is, you don’t mention that the Check Engine light came on at anytime. It should have if the converter was destroyed with a code referring that the catalytic converter efficiency was below threshold.



It sounds like it may have been a defective part. If they replace it again, you might be okay.

I went throught the same thing several years ago but I got my catalytic converter/exhaust manifold replaced in my 98 Civic DX for less than $500 by going to a muffler shop and having the guy find someone in California who rebuilds them. It was better then the $650 that the dealer quoted. The next time I will consider replacing it with a header and a regular universal catalytic converter. It will probably mean a custom exhaust system and extending the wires that run to the Oxygen sensors. I plan on keeping my car for a long time will probably need to replace the original exhaust system in the next 75,000 miles.


Well… I definitely have an engine, and it sounds rather good for as many miles are on the car. I have not once had any light come on in my car… oil, engine… anything. Neither did its previous owner (my dad). As far as I know, I did not run through any deep water in the last week and a half, although anything’s possible. Something could have splashed it the last time it rained. I always use the correct octane fuel. Again, never once did I have a Check Engine light come on… even when my exhaust manifold cracked. Perhaps Honda caught it before it started really exhibiting symptoms… I only brought it in when I started hearing the awful screeching/shrieking/squealing in the last few days. It would have only been going on for a few days, because I just passed my inspection. Or perhaps that particular light has burned out >_>. As soon as this little hellspawn hit 150,000, stuff went bad all at the same time. Another thing I should mention is that Honda wrote that “shields are missing”. That seems like something I would noticed if it had fallen off. One more thing I will need to investigate when I visit the mechanic who replaced my original exhaust manifold/CC tomorrow…

Thank you for your info… I appreciate any education about my car that I can get. I don’t know nearly enough about it.


This is what I am hoping as well, as the car is running fine otherwise (for now). I will find out tomorrow, I suppose, when they examine it further. I find that I’m slightly annoyed that the exhaust manifold and catalytic converter are attached and must be replaced together, now that I’ve had the system go bad twice. It’s not even the cost that kills me, it’s all of the visits to the mechanic/dealer, the ordering of the part (are they shipping it from Japan or something?!), and the worrying that the car is going to either spontaneously combust or just die while I’m driving it to be fixed. If my engine or another extremely expensive part of my car is responsible for the exhaust going bad, that’s it. It’ll be time for a trade. I love my Honda and Hondas in general, but with nearly 150,000 on my car in 5 years, I feel I’m already pushing my luck by hoping that it makes it to 200,000 w/o a major failure. Thanks for sharing your past experiences!


I am not sure I would give up on your car yet. This cracked exhaust manifold is one of the few problems I have had with my Civic. Mine now has about 175,000 miles and is four years older than yours. Once this problem is solved, this car should have many trouble-free miles ahead. To be fair, I did drive my car through Hurricane Irene and I was pushing it pretty hard at that time. Also, I think Honda designed the catylitic converter and exhaust manifild as one piece to (a) lighten the vehicle, and (b) make more room for a sophisticated catalytic converter that signifigantly reduces emissions. I admit that I questioned the wisdom behind a $700 catalytic converter, but this is a good all-around car with a useful life of more than 250,000 miles. Don’t get rid of it just because of a single problem.


Okay, so time for an update: I took my car to the place that had replaced my catalytic converter/exhaust manifold, and they claim there’s nothing wrong with it at all, save that it’s missing the cover (I don’t even want to know, but they claim it’s not important to replace). The heat shields are all in place, and I test drove it with the mechanic, and we both heard the noise. He said it sounded like a vibrating/rubbing metallic noise, and that he could spend all day trying to find what was causing it. He did make an effort, and he adjusted some of my heat shields, perhaps thinking that they were vibrating, but nothing has worked. I heard the noise again on the way home, and gave up. I went home, called Honda again, and explained the situation. I told them that it’s highly unlikely that my catalytic converter has gone bad, seeing as it was 1.) Just replaced 2.)No Check Engine light 3.) No other percievable problems with the engine or exhaust. They told me to bring it back, as the clicking/tapping noise by the driver’s side door has also not been fixed by “clips” that they put inside the fender. I think maybe they should take those clips OFF and give me my $20.00 back for them.

Now I’m just torn between the dealer (Honda specialists) and the tire/auto place that is AAA approved for maintenance. I’m considering trying another Honda dealer if I can’t get any satisfaction from the one closest to me. I don’t know what could possibly be making the noise now, but it’s something that only happens (or only gets loud enough to hear) when I’m idling, slowing down to a complete stop, or accelerating from a complete stop. Everything else sounds really nice… engine, brakes, no transmission issues that I’m aware of, and all of my belts and hoses are new.

I’ll be happy to keep my Honda until the transmission, A/C, or engine dies. It’s cute, extremely red, and it gets excellent gas mileage. And then I’ll be happy to buy a new one. One that isn’t possessed.


Well, it does it at idle so that should make it easier to isolate. A little probing around with a long screwdriver as a stethescope and you may find that an accessory bearing is on the way out.

I will disagree that the cover is unnecessary. Anything that is non-essential would never be installed in the first place. That cover protects whatever you park over from the very hot converter. Most are clamshell designs that encase both the bottom and top of the converter. These are required IN ADDITION to the heat shields attached to the undercarriage of the body to keep the converter heat from affecting the car as well as the ground. Obviously, since you’re driving around without it, you can get away with no cover under most normal operating conditions (engine runs normally and not parking over combustibles). It’s when something goes wrong and the converter runs abnormally hot that you really need this protection. I’d expect a fully priced, OEM replacement part to have all the normal protections and would not settle for less.


I agree. For $900 you should expect that cover and every heat shield to be in place.


Well, given that, I should probably stop parking over dry leaves = ) and have Honda order that shield/cover if they can. I don’t know whether it fell off after the part was replaced, it was never put on by the mechanic that replaced it, or whether it had fallen off while my father owned it. Either way, I will look into getting one. Although, if I set those leaves on fire, maybe I wouldn’t have to worry about that horrible shrieking noise anymore…

I think I will not be poking around in my poor car with anything at this point, but I feel like printing out this whole page and giving it to the Honda mechanics with a smile. I’ll suggest nicely that they poke around and look for something that might need to be tightened that’s NOT the belts.


If Honda still insists that my catalytic converter is busted, is there a way they can prove it to me… for example, should I be able to ask them for a failed emissions test, or might they be able to demonstrate somehow that there are chunks of stuff rattling around in there? Or is there a way I can check myself at home?


When you say “missing”, did you mean that somehow the engine might be faulty? I read that as “engine no longer present in car”. I still think my engine is okay… the car has regular oil changes and after babying the car, I think it actually sounds better than it did when I first acquired it.


They dropped the cat before putting it in. They might have thrown it onto a bench or the floor during shipping.


In my limited experience, converters that break apart usually rattle not shriek. If it’s shrieking, that might indicate a restriction. If there’s a restriction, it can be verified by placing a pressure guage in the forward O2 port and measuring the exhaust back pressure. I’d also think that the converter efficiency would be low to non-exsistent and so sniffing the exhaust gases with their emissions equipment should show that as well.


Okay, I’ve finally gotten results. I told Honda it was probably NOT my catalytic converter and why, explained the whole situation again, told them how to road test it so they could hear the noise, and 2 hours later, the service manager sits down with me and puts two pieces of metal on the table. Turns out one of the supports that holds the catalytic converter in place had snapped in half, probably awhile ago, because it was rusted. It was vibrating like hell and making the noise. They removed it and ordered another one, and they also ordered the heat shield/cover and explained why it would be a good idea for me to have it.

I feel a little better about my Honda dealer now, or at least the service manager that worked with me. He thanked me for helping them find it, physically showed me the car and what needed to be done and why, and praised me for keeping up with the maintenance (I called their attention to the fact that the car had never had the transmission fluid changed or new spark plugs, and also that it desperately needs an air filter.) I also feel better that it was technically the catalytic converter, so they weren’t just making up some random expensive part of my car to replace. Though the fact that they wanted me to replace it is still troubling, it’s less so than before. Also, my car is finally SILENT, and eerily so. The only thing that makes noise is the left front fender… apparently there’s something stuck in there (probably a stone), and I don’t want to pay Honda $80+/hour in labor to pull off my fender and pull it out. They assured me it’s not the suspension, so I’m not worried about that for the time being. Thanks for everyone’s help and advice… this is a great site!