P0420 on 2005 Honda Odyssey (ONLY 41,000)

I just bought a used Honda Odyssey last week with 41,000 mi. As soon as I drove it off the lot the check engine light came on. I read the code with my Actron PocketScan when I got home and it said P0420. I erased the code and it came back within 15 miles. I took it to a local mechanic and told me it was probably dirty sensors. He erased the code and sent me on my way. The service engine light came on right after I left his shop. I then took it to a honda dealer and they told me it was an intermittent problem and to bring it back if it happened again. It did. The odyssey is going in the shop AGAIN next week. Can anyone tell me what the problem might be? I think we pretty much phased out dirty sensors or an intermittent problem. I understand that it isn't very likely to be the catalytic converter because of the low mileage but what else could it be. I am just getting very frustrated why I am $200 in the hole from service checks and my van is no better when I bought it. If anyone could shed any light it would be very much appreciated!

You're 200 dollars in the hole for service checks because you took it to the wrong shops. Whoever told you that dirty sensors would trip that code have there head up there arse! As for the dealer yeah if the code setting criteria is clearred by that idiot then it's going to be easier to troubleshoot when there's freeze frame data stored for them to analyze. Alot of times that code on lower mileage vehicles is repairred with software updates. It loosens the code setting criteria to allow for fuel quality etc, I would think if this was available on your van the dealer will know about it but if they only hooked up the code reader to pull the code and give it back to you then they might not have checked for those bulletins if they're applicable. Your Converter may still be covered under warranty and low mileage doesn't mean the converter can't be bad. ! But the dealer can confirm if it is or isn't and properly troubleshoot it. Ah the joys of used car lots eh!

Unless there is something going on I'm not aware of, your converter is still covered under warranty. Federal law requires emissions related components to be covered 60,000 miles, and from what I understand this wiil soon be going to 100,000. Take it to a Honda dealer and they should fix it for you at no charge.

if you bought this car used, I would check everything over first. See if there are any damaged sensors or exhaust leaks. has any one done any fuel system cleaning? the chemicals used to clean fuel injectors will burn out O2 senors setting off codes. check MAF sensor, air leaks, and other codes.

Thanks to everyone who has responded. Taking the Odyssey back to the dealer a second time they decided it was time to replace one of the catalytic converters. They charged me $577 and it did fix the problem. I went back to my dealer to see if they would take care of the charges. The dealer had dealt with this honda dealership where I took my van to be fixed before. My dealer called them up and chewed them out! He knew that the converter was covered under warranty and they should not have charged me. He said they would have pocketed the warranty money. Lone behold the Honda dealership called me back and told me they were going to refund my money. They also said that the tech's at Honda also want to replace all of the catalytic converters and all of the O2 sensors at no cost to me. I guess they might have had early on problems with the 05 Odyssey's. Anyway the problem has been solved. I believe Honda has a good product but I have to say I have an extremely bad taste in my mouth from their service side. Hopefully I will not have to take the Odyssey back to get fixed but if I do it will be a new dealership. Thanks for everyones help.

So you were dealing with two different Honda dealerships or do you mean you're used car dealership that sold it too you. Im not sure why you have a sour taste in your mouth. The dealer fixed your van for you at no charge to you at a substantial cost to them for parts and labour and you didn't even purchase it from them? The nerve of them!

The bought the used Odyssey from a GM dealership. I am not angry at the GM dealership because they are taking care of the problem. I do however have an issue with the Honda dealership performing the repairs. I do not like shady dealerships. But that is not the only reason I am not happy with this particular dealership. I had called last Tuesday at lunch to see if they had the new catalytic converter installed yet. They said they had not but it will definetily be finished by 5:00. Driving half way to the dealership (40 miles from my house) they had called me and told me it will not be complete until tomorrow. They told me they would give me a discount because I had already traveled half way. The next day when I picked the van up the discount came to $12.41. What equation did they use to calculate this!? For a $590 repair job a $12.41 discount is like kicking me while I am down. Also I was scheduled to take my van in today to get the new catalytic converters and O2 sensors installed. I called last night to verify the appointment and the guy had forgot to schedule it! Now I have to take the van in next week. What a hassle! True the Honda Dealership is taking care of all of the costs for this but they are not paying for my time, gas, and taking 2 vehicles to and from the dealership 40 miles one way. I don't know I guess if one thing happened I could have overlooked it but just feel like I have gotten the shaft from this dealership. I will definitely use a different dealership to fix my Odyssey next time.

Be sure to tell them that!