My 1998 Honda Accord LX (LEV, 121,000 miles) just started showing its check engine light today. (Prior to this, I noticed that my car has run a bit roughly while I am in gear at a stop light.) I immediately went to my local AutoZone store and had them hook it up to a code reader. Their tester showed a P0420 code, and their guy said that in most cases this meant that the catalytic converter is bad. Granted, there may be other mitigating factors at play here, but this seems like it may be one thing that I’m resigned to do.
Since I live in the great state of Indiana, I don’t have to worry about emissions testing. So, my question is this: Do I absolutely have to buy a catalytic converter that’s certified for use in all 50 states in order to make my car run right, or can I get a 49-state converter and pay less for the converter in the bargain?
Any insight on this is welcome. Thanks in advance for your advice!
Short answer is you need to either remove or replace the catalytic converter.
To remove it is a violation of federal law.
If you don’t either remove it or replace it, it will soon clog you exhaust to the point that your car won’t out-run a old man using a walker (Ref. Office Space).
Replace it, and we’ll all breathe easier. Replacements are pretty cheap if you find a universal one that will fit your car. Check Honda Accord message boards; they should be able to give the make and model of what you need, then go to a muffler shop and have them replace it.
P0420 can be tripped by another problem in the engine, that shows up as a cat efficiency code. See this page for some possible causes.
It would be a stone bitch to shell out for a new converter and have a P0420 pop up again the next day.
This guy claims you can clean the converter. Disclaimer: I have never heard of these procedures and have no idea if they work or not, but if you are feeling lucky…
Thanks for the link, Rick! You’re right, it definitely would suck if the P0420 popped up again if I swapped out the catalytic converter. I’ll check out that YouTube video in a few minutes, but I’m watching the debate at the moment and I’m not the world’s best multi-tasker.
Excavating (for a mind): Luckily, the catalytic converter on my car is the original OEM bolt-on model, so replacement should be relatively easy – provided I don’t round-off or break any of the mounting bolts. I’ve seen a lot of converters that are cheaper but would require welding, so I’d rather spend a few bucks more and try doing the work myself.
Samclem: I’m pretty sure that a generic would fit into my existing exhaust system, but I’m trying to make sure that it can be installed without triggering some other code to pop up after installation.
Good point. I’ve had this car for five years now and haven’t checked the spark plugs or the condition of the EGR valve. I’ll probably look into those first, although the EGR valve ain’t exactly cheap if it needs replaced. BTW: air cleaner is new and I’ve never cleaned the throttle body – as if I knew how to do that! Timing belt and water pump were also changed last year and valves were adjusted at that time.
It might have been different back in '98, but with the newer Hondas the LEV model is the normal federal compliant* model, whereas the ULEV is the California one. The emissions sticker under the hood should say either “complies with all Federal…” or something like “complies with all federal and California…” which will tell you for sure.
If you do have a 50-state car, I suspect using the wrong converter won’t turn the CEL off, since the converter performance will be less than the computer on your car is expecting. You certainly don’t have to use a Honda OEM converter though.
*It’s not “49-state” anymore because several other states follow the California standards now.
Unless and until the converter gets restricted, it won’t affect how the car runs. If it does get restricted, the symptom isn’t rough running, it’s loss of power as excavating mentioned. Whatever is causing the rough running may be damaging the converter, but the converter, damaged or not, is not causing the rough running.
First, find and fix the rough running problem. Then have the car tested properly to identify the cause of the P0420 code. If it needs a converter, get one appropriate for the car (i.e., don’t get a California type if the car isn’t designed for California emissions), and if you don’t want the code to reappear prematurely get a genuine Honda converter (field experience shows that many aftermarket converters do not work well enough for very long – sometimes less than a month).
If the car has the 2.3 engine the spark plug interval is 30K miles; if it has the 3.0 it’s 105K miles. Either way it sounds like it’s way past due for plugs. I’d replace them before even looking at anything else.
As far as I can tell there is no loss of power, which I thought was a little odd if the exhaust system was being restricted. My mileage has remained the same, too.
I just went back to AutoZone at lunch and picked up some new spark plugs, so I’ll pop them in tonight. I pulled the #13 fuse on the passenger-side fuse box for about 10 seconds to reset the CEL so I can see if there’s a reoccurrence. I also popped the hood open and checked the PCV valve to see if it was bad or not. The valve looked dirty and wouldn’t rattle when shaken, so I went ahead and popped a new one in while I was at the parts store. Could be wishful thinking, but I think the car seems to be running smoother. I’m anxious to see how the spark plugs look when I pop them out…
The P0420 code, as Rick mentioned, has to do with the catalytic converter’s efficency at catalyzing the combustion of remnant fuel in the exhaust. It typically does not relate to restriction or mileage issues.
Okay, the spark plugs have been changed and so far so good. The old plugs were fairly free of deposits, but the central electrodes on all of them were fairly worn down. What deposits there were had an off-white color and were lightly distributed.
The car is running a bit smoother now and the check engine light hasn’t lit up yet, but I’ve only put on about 20 miles on it so far. I don’t think that the problem has been fixed by these simple things, but I feel better having done these overdue maintenance tasks.
FWIW, I’ve driven 70+ miles so far with no CEL being displayed. It’s probably a bit premature to say I have the problem fixed, so I guess I’ll have to wait and see.
