My car is a 2003 Honda Accord V6, 3.0, 5 speed Auto transmission. I have a P0420 code, for the bank 1 (rear) warm-up catalytic converter, the one in front of the firewall and bolted to the engine. I had the car checked at the muffler shop and asked if there were any exhaust leaks, according to the tech there are none. I have considered ordering the parts from a Honda dealer, perhaps Bernardi or HondaPartsNow, and I have the Honda manuals -- the big one (2003 version) and the later V6 supplement. In the supplement, it says that the intermediate shaft and exhaust pipe are to be removed. To do that, a whole host of other things need to go down as well. This is to facilitate removing the cat from the bottom of the car. There apparently is no room to remove it from the top. I can easily get to all 7 nuts of the cat: 3 on the exhaust manifold (very rusted, may have to cut or grind off) and 4 on the top (not so rusted, PB Blaster should work).
My question is: Is it possible to lift or move the engine forward a few inches so I can get the cat out from the top? Even if I have to disconnect some hoses, drain the coolant, whatever, it still beats taking out the shafts, being scared of seals falling out, etc. Basically what I'm looking for is a quick way to do this, without getting too involved because I only want the one cat out, I don't want to disassemble my car. Thanks for your help if you can!
BTW, I am by no means a car mechanic; all I have are a pair of Rhino ramps. No jack or jackstands, but I will get them if need be.

 

hey, what part of ri you in...

anyway i have the 2.2L and i replaced the entire exhaust mani back, i too am having the p0420 issue, it is aggrivating me pretty bad as i spent nearly $1000 fixing this pos car for inspection.

i did see a thread about getting rid of the p0420 code after a cat install ill post it if i find the thread.

 

hey REPOST!

so what part of ri you from

anyway i have recently replaced my cat for inspection and i am also having the p0420 issue, i went to frenchtown and they said it most likely needs a top end cleaning, to get excess carbon out of the engine...

i have no clue what to use besides seafoam, but he didnt recomend it so ideas???

i also saw a thread on this exact issue and how to fix it in a diy setup..
when i find it i will let you know

 

I don't think you should assume the converter is bad. The code probably came up, because the sensor was reading something different from what it should. The sensor might be the problem, and not the converter. The O2 sensor is a lot easier to change, and it's cheaper than a new converter. You need to test the sensor to find out. Don't just guess.

 

Don't replace your cat converter just yet. Apply a couple of bottles of cataclean (amazon.com) and see if it takes care of the issue. Your cat might have been clogged or dirtied and just needs a bit of a chemical clean up. I've used 2 bottles of Cataclean and a bottle of SeaFoam (total of $57) and my CEL has not come back. Plus my average MPG has increased 10%.

And I don't buy the idea that the honeycomb inside the cat gets crumbled up and sucked back into the engine. There is a third cat converter underneath the car that does not get hooked up to the computer via any sensor and never sets any code. What if it goes bad? No light would come on, right? Honda wouldn't let that happen unless... it never goes bad!

 

Thanks to all of you for your responses. Okay....I did try several bottles of Cataclean from Pep Boys. I even tried Scotty Kilmer's laquer idea - poured a gallon of laquer thinner into the tank (which was 1/4 full), 2500 rpm for 1/2 hour, then filled up the tank. None worked. So I put the car up on the ramps and took a look. The rear converter shield was broken clean off, and floating loose. That waas causing a slight rattling while driving. That gave me the opportunity to check out the converter itself: it is severely discolored, like it was overheating. Last summer the car was missing and I replaced an ignition coil. It's possible that the ignition problem messed up the cat. I also replaced the lower HO2 sensor of the cat. Same problem. So, assuming it IS the cat, the original question: how do I get it out from the top of the engine as opposed to ripping out the shaft from the differential, messing with the ball joints, removing the exhaust pipe and basically disassembling the underside of the car? I was toying with the idea of removing the rear plug coils, hoses, wiring, etc. and then with a big pipe, having someone pry the engine forwards while I removed it. Is this sheer folly? Should I back slowly away from the tools and have a professional do it the Honda way?

 

When you said none of the additives worked... what do you mean? Did you reset the CEL and it came back right away? Or you did not reset the CEL and it hasn't come off on its own? If you never cleared the code, I believe it might take quite a few miles for the CEL to come off.

Mind taking a picture of the "discolored" cat?

 

Even a properly-working cat gets pretty hot. Some discoloration is normal, but without seeing it...? Have you looked at em on other cars for a comparison?

It certainly is possible for the ceramic monolith to break up, but it's not as common as other things. Certainly heatshields are the first thing to check when it's rattling.

The catalyst can overheat from a misfiring engine, and that can lead to some melting in the monolith, but again you check for that rather than blindly replacing the cat.

 

I used a scan tool to clear the CEL. I clear the code with the engine on but not running. After the code is cleared, I start the scan tool setup procedure again, but this time I start the engine. I navigate to the Drive Cycle Monitor, then I would drive the car on the highway. There's 5 codes when the engine is cold, and after the first 1/2 hour of driving, only Catalyst and EVAP have not cleared. Stop and go traffic takes care of the EVAP. The manual says to drive at 55 mph with cruise control on for at least 2 min. After about 5 minutes of driving, the code is thrown. Each time, I would reset all codes with my Actron CP9580 scan tool. I have gone through 4 bottles of Cataclean, 1 gallon laquer thinner, 4 bottles of Lucas Upper Cylinder and Injector Cleaner as a Cataclean chaser (Cataclean, fill tank, Lucas, fill tank, lather, rinse, repeat). My next step is to get a Pyrometer from Amazon to check the good warm-up cat temp, and compare it to the suspected one. There's 3 cats on my car: 2 bolted to the engine front and rear, and one underneath the car. I'll check the front cat input and output temperatures and compare it. When I asked the Meineke tech about exhaust leaks, he never tested the thing, just looked and said there are none. So I will go somewhere else and have them put an actual smoke machine to test for leaks. This might take me a while, so stay tuned and I'll report back my findings. Thanks yall!

 

Sounds like you've checked a lot, & looking like it IS a bad cat. It just seems like most people who post have done very little actual checking and they want an internet-answer without doing any testing for themselves.