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Discussion Starter · #1 · (Edited)
Been pulling a po420 code showing bank 1 converter operating below threshold. My odyssey has close to 270,000 miles on it now but runs pretty good still so I am looking into replacing the converter. I have already tried the cleaning technique with a gallon of lacquer thinner but code reappeared after about a week.
1. I want to confirm first of all that the bank1 converter is in fact one toward the front side of the car engine and radiator?

2. Secondly I noticed a considerable difference in price between the OEM CONVERTER and after market ones. According to my reading some of the aftermarket converters can be problematic and not clear the codes or only last a year or two before having to be replaced again. I am not necessarily looking for the cheapest brand but am unsure I want to drop close to $700 in the OEM part if I can find a reliable aftermarket converter for much less, especially on a vehicle with 270K on it.
My second question, has anyone tried and had success with any of the better aftermarket brands on these odysseys? I was looking at the Bosal brand on Rochauto.com. It is more expensive than the other brands but about half of the OEM part.

input and advice much appreciated!
 

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My .02$, is that there are several types of failures, some you can live with and some you can't. A plugged converter you obviously can't live with, but being under the recommended efficiency, especially after the mileage you have put on the vehicle doesn't seem like a sin. I have also found issues with aftermarket converters that didn't keep the CEL off for long and some not at all. Maybe in the cases where it didn't work at all, there was a contributing factor like a slight exhaust leak. I can say that my daughter's car has an aftermarket Walker cat and that car(Pontiac Vibe) has never had a CEL. Surprising because there was a SIGNIFICANT exhaust leak that I fixed and that didn't cause a fault. I read that different manufacturers may set the efficiency bar at different levels, but I am not sure I believe that.

If it was me, and I was getting good fuel economy and the van ran well, I might leave well enough alone and clear codes as the come up. There are also other ways to eliminate codes, probably all illegal, but I think you might still be processing exhaust, if you don't remove the converter and make the vehicle think its still at the efficiency it needs to be at.
 

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Depends where you register this van, but at this mileage, I would beat them out and fool the sensors. I live in FL though, you can do whatever you want here.
 

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I also have a theory about getting past emissions without that extender. In nj there is a camera under the vehicle that displays as the car drives over. I believe they are checking for cat removal but they could also see an extender if they were paying attention
 

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If you are looking to do the right thing (I support clean air), the Walker or Bosal converters are reliable brands. Go for extra precious metal and stainless if you have a choice.

Bank one is, by OBD definition, the bank including cylinder #1 (defined by Honda), which is the bank closer to the firewall on your ODY. Bank 1 is also the sole bank on a single exhaust. Per Walker, your Ody has a converter on each bank, next to exhaust manifold. It also has a third converter, back after the Y pipe joins into one. The O2S setting the p0420 is likely right behind that third converter, and it is the most likely converter to be bad.
 
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do the right thing (I support clean air),
I also support clean air and would never intentionally disable emissions. I could use some education here because I always assumed that catalytic converters will set a code when they are measured to fall below some efficiency, say 80%. When the car was new what percent did it attain? What kind of improvement do you get from the aftermarket units and for how long? Hoping that somebody might respond to clear up whether an aftermarket cat is better now and in a couple years than the fading oem unit that is still functional,although diminished
 

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I also support clean air
Supporting clean air? How exactly? Driving 15 y.o. van is a good way to support personal finances, no clean air support there at all.
I am getting model X next week, will keep old Ody for long trips, that's how I support clean air.
 

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Repairing/maintaining so that the vehicle continues to meet emissions standards in effect as of date of manufacture is better for the air we breathe than allowing the vehicle to exceed the standards. Really, a simple concept to grasp. That's the real world choice for OP.
 

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Supporting clean air? How exactly? Driving 15 y.o. van is a good way to support personal finances, no clean air support there at all.
I am getting model X next week, will keep old Ody for long trips, that's how I support clean air.
IMHO, driving old car which still meets clean air spec is probably better than getting a new car and junking the old one though. No? building a new car and junking old contributes to air pollution. Model X, is cleaner while running, but building and disposal has larger footprint than regular ICE car. (I am NOT against a EV. My next car probably will be an EV, just that it isn't time for me to get rid of my working car when I drive so little and can probably drive the car for years)
 

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And then there's the matter of where the electricity to charge an EV comes from. Just because the pollution has been moved upstream doesn't mean it's been eliminated. And the chemicals and metals in those batteries........
 

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Supporting clean air? How exactly? Driving 15 y.o. van is a good way to support personal finances, no clean air support there at all.
I guess I was trying to open this up for someone that knows about catalytic converters to chime in. I support clean air by not defeating emissions plain and simple

Congratulations on your upcoming purchase of a Tesla but don’t look down on forum members that are not in your situation. Thanks for others reminding us that an EV isn’t made and run without some environmental impact.
 

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I guess I was trying to open this up for someone that knows about catalytic converters to chime in. I support clean air by not defeating emissions plain and simple

Congratulations on your upcoming purchase of a Tesla but don’t look down on forum members that are not in your situation. Thanks for others reminding us that an EV isn’t made and run without some environmental impact.
Not trying to upset anyone, just saying - driving old vehicle is bad for environment.
 

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I also support clean air, but my question for the OP was how long does it take for the CEL to come back on after it has been set. If it takes a couple of weeks the light to come back on, than it is being triggered by a driving situation that doesn't occur very often. It also means the OP is in compliance for 99% of the time, which is OK by me.
 

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Discussion Starter · #15 ·
I also support clean air, but my question for the OP was how long does it take for the CEL to come back on after it has been set. If it takes a couple of weeks the light to come back on, than it is being triggered by a driving situation that doesn't occur very often. It also means the OP is in compliance for 99% of the time, which is OK by me.
Light comes back on after one to a few days. May even go off by itself periodically but comes back on in a day or two.
 

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Discussion Starter · #16 ·
If you are looking to do the right thing (I support clean air), the Walker or Bosal converters are reliable brands. Go for extra precious metal and stainless if you have a choice.

Bank one is, by OBD definition, the bank including cylinder #1 (defined by Honda), which is the bank closer to the firewall on your ODY. Bank 1 is also the sole bank on a single exhaust. Per Walker, your Ody has a converter on each bank, next to exhaust manifold. It also has a third converter, back after the Y pipe joins into one. The O2S setting the p0420 is likely right behind that third converter, and it is the most likely converter to be bad.
Question, if it is the farthest O2 sensor behind the 3rd converter throwing the code, then how does it know which bank to tell you is problematic since both bank1 and bank2 converters dump into in one pipe feeding into the 3rd converter? Just trying to understand how this whole thing works here. I am pulling a P0420 code which my scanner tells me is bank 1 converter.
 

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That is a great question. I remember looking into codes like that and, being reluctant to change out an expensive part like a catalytic converter, I could easily find a whole list of other conditions that might lead to this code, from intake restrictions to exhaust leaks and everything in between. Even the oxygen sensor that provides the reading that is used to make this determination might be faulty. If I knew more about how to read the real time data of a running vehicle I might be better able to understand what is happening here, but I don't have the knowledge or tools.

Actually just watched Eric the car guy and he used a non-contact thermometer to check the inlet and outlet temps of the converters to identify which were not doing their job. In one case he read a converter that went from about 200F to 400F inlet/outlet and said that was a good sign. Others with failing cats might show a higher temp at inlet. Interesting.
 

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did a little more reading on O2 Sensors and Catalytic Converters. Seems like 02 sensors can definitely degrade over time and there are replacement intervals for them. I don't think I have ever replaced one unless a code said it specifically failed. My MO is to look for bigger clues that something is wrong like specific codes, running rough or changes to fuel efficiency. The catalyst in the converter is also a substance that will be used to perform a function and will degrade over time. Add to that the Odyssey's VCM expelling oil through the exhaust, fouling plugs leading to unburnt fuel also being sent through the exhaust and you have factors that lead to diminished life of a converter. You did get 270K miles on the originals which is pretty impressive.

My guess at this point is that the health of the converters is measured by the three oxygen sensors. There is a sensor for each bank and one at the exit of all the converters. The evaluation is being done by computers and can be adjusted and evaluated may times a second. The computer must see the changes in the faulty bank's initial O2 sensor's fuel reading not having the expected impact on that final sensor. Perhaps it even goes into a test mode periodically keeping one bank constant for a second or two to vary the other. Glad I don't have to design any of this.

Modern computers in cars are pretty amazing and make some things so much easier, like a periodic tune up. I read somewhere that a misfire on a modern engine is determined by a reduction in the rotational speed measured in a sensor (crank position sensor?). Amazing, it picks up a change in rotation speed while running for a single cylinder periodically not firing.
 

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FYI, most people here replace all 4 O2 sensors at 150,000 miles. Even if they are working fine, it's good maintenance to do.
 

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I have a periodic low efficiency code on my Prius. In their forums somebody suggested that I just bite the bullet and replace the catalytic converter. The forum member posting said there was a person in TX who he dealt with that recycles converters and the $ from the factory converter would pay for the replacement. I didn't pursue it, but it might be worth a look around to see what a recycler would give you for it.
Several years ago I had a 2000 Ford Explorer parts car. I listed it to sell parts and got $150 for the rusty original cat. Somebody stopped by to pick it up and probably turned a decent profit on it. I had no idea what the scrap value was.
 
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