Hi All. I've got a 2013 CR-V that I bought used last year with a little over 207K miles. I've recently been battling a P0420 code. I've replaced both O2 sensors with Denso units from RockAuto. I've removed and re-installed the catalytic converter a couple times. The first was just to inspect it and see what condition it was in. The second time was this past week to attempt to clean it. I soaked it in hot, soapy water in hopes or cleaning any contaminants that might be causing any issues. The converter seems to look fine as far as I can tell. My only concern with it is that I don't see any kind of markings on it to make me think it is an original OEM Honda and that it was replaced before. I've read that anything other than OEM Honda parts might not work properly. I'm even worried about the O2 sensors I've installed at this point since they didn't come from a Honda dealer even though they are Denso like the OEMs are.

I don't have anything other than a basic scan tool so I can't monitor the O2 sensor voltages to verify what's going on. I'm going to try to test for exhaust leaks next I suppose. I don't have a smoke machine but I'll try to make up a homemade one or try using air and soapy water. I'm not sure what else to try next. I've got a infrared thermometer so maybe I'll try getting the car hot and check the inlet and outlet temps on the cat and see if that looks as it should. Anyone else have any suggestions that doesn't involve a few hundred dollars for a new scanner or a grand for a new cat?

I'd love to be able to figure this thing out without taking it to a shop to have them throw parts at it. I'm in NC so we have emissions testing and I'm due for inspection before the end of August. Thanks.

 

You don't have a scan tool or it would show live data. You have a code reader. You need a new cat. Do you have emissions inspections?

 

Thanks for the correction. Yes, I understand the difference between a scanner and a code reader and that I indeed have a code reader. Yes, I'm in one of the NC counties that still require emissions inspections as stated above. If I didn't have emissions inspections then I would be prone to just let the code go for now since the vehicle is running fine and fuel mileage seems normal. Can you tell me what exactly leads you to determine that I need a new cat? Is it simply the fact that I'm getting a P0420? Is it because the cat may not be Honda OEM? I was looking for more input or suggestions other than just throw the first part on the list at it since these codes can be tricky sometimes. Thank.

 

If the sensors are working correctly and the exhaust is in good order the cat is not storing enough oxygen and needs to be replaced. A lot of money has been spent trying to fix these without doing it right just end up having to get a new cat anyway.
OEM will outlast the aftermarket cats.

 

Do you know if there is any type of part number, emblem or other markings on an OEM Honda cat to make it distinguishable from an aftermarket part? The catalyst element in my cat looks fine and isn't broken or clogged from what I've looked at from both ends. It has all of the heat shields on it as it should. I hate to throw $750+ at a new cat when I can't verify the voltages on the O2 sensors and can't even have confidence that the new Denso sensors that I installed are good enough to be Honda OEM just because I didn't buy them from Honda. Thanks.

Also.....I just now did a soapy water test to check for exhaust leaks since I don't have a smoke machine. Pressurized the system with a shop vac connected to the tail pipe. I've got a leak around the exhaust flange doughnut gasket at the bottom of the cat. Exhaust leaks are listed as one of the possible causes of the P0420 code. I guess I'll find a new gasket and see if that makes any difference. I'm driving multiple drive cycles and going 50 to almost 300 miles between P0420 codes coming back. Seems like a bad cat would trigger a code a lot more often than that. Any thoughts? Thanks.

 

The cat can look new and not store oxygen.You need to understand how the catalyst works.

 

Yes, I understand that it could look new and not work properly. That's not any part of what I was asking. You're doing a fabulous job of not answering the questions that I ask and telling me the simpleton, knee-jerk reaction of throwing a cat at it. No response to the question about what an OEM converter might be marked with as opposed to an aftermarket one? No response the update that I added to mention that I found an exhaust leak at the donut gasket post cat prior to the downstream O2 sensor that might be causing it to read incorrectly and think the cat is bad? Are there any other moderators or knowledgeable folks here who would care to actually read my posts and attempt to answer questions to be helpful? I'm not trying to be a dick but I just find it difficult to believe that the standard answer here is just to replace the part that the code says. I've never seen any good mechanic recommend that. Thanks.

 

I'm a retired shop owner and when I have a customer like you I usually tell them to take it somewhere else.
There's only one way to cheat this and it requires reprogramming of the PCM.
Is your exhaust solid? Yes, Sensors are new and working correctly? Yes You need a new cat. PERIOD.

 

I'm not trying to be disrespectful but you were not answering my questions. You just wrote "Is your exhaust solid?". Obviously you are not acknowledging the fact that I told you that I just found an exhaust leak when I checked it earlier this evening and told you exactly where it is leaking. What are you going to do as a shop owner if you tell me that I need to replace my cat and then after replacing it, I still get the error code because I have an exhaust leak? Are you going to refund me the price of the cat and then find and fix my exhaust leak? I seriously doubt it. I've watched enough good mechanics on YouTube that teach you to troubleshoot an issue rather than just "firing the parts cannon" as they call it. Any customer like me isn't going to want to pay for replacing a catalytic converter unless it's actually bad. I'm not trying to cheat anything. I'm trying to fix the problem. PERIOD

I'll just leave you alone now since you haven't really answered any of my specific questions where I'm trying to learn something and fix something. Thanks again.

 

Thanks guys. I didn't mean to start a debate about repair shops and their ethics but that's exactly why I came here asking questions. I try to repair any issue myself if I'm able to figure it out because I don't want to end up paying a fortune at a shop where they just throw parts at a problem until it's fixed. In this particular case, if I went ahead and replaced the cat with the exhaust leak at the outlet flange then it would probably fix my issue if I replaced the gasket along with the cat and never been any the wiser and be out $700+ unnecessarily (whether I do it myself or let a shop do it). If I still have the issue after fixing the exhaust leak then I'll either replace the cat or verify the new O2 sensors for sure by purchasing a scan tool or borrowing one just to make sure the sensors point to a bad cat.

I'm in North Carolina so we just go by the federal emissions standard and not CARB standards. I was aware of the sparkplug defouler trick but I not interested in doing that. I want to fix the issue properly but only by replacing what is actually causing the issue. I've ordered a new flange gasket so I'll retest once that's installed. I currently don't see any codes set or pending. If I have a bad cat, shouldn't this thing set a code fairly quickly? Since the last time I cleared the code I have driven at least 8-10 drive cycles and over 80 miles. I know it is supposed to set a pending DTC when it first sees an issue and then set the actual code if the condition is there on the next drive cycle. Thanks again