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2006 Odyssey EX 268,000 miles
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Discussion Starter · #1 ·
Hello friends. I have recently pulled a catalytic convertor code on my '06 Odyssey. Just to be sure I cleared the code and within a few days it showed up again.
My scanner said most often caused by a fuel trim running too rich on the same bank. So it looks like I am going to have to put a new cat on it, but do I need to get the fuel trims adjusted also? I have no working knowledge about fuel trims. How they work, how to adjust them, or even how to know if they need to be adjusted and what proper tolerances should be for them.

Last year I adjusted the valves, cleaned the EGR valve, replaced the PCV valve, new plugs, new wires, all new O2 sensors, 6 new fuel injectors, new valve cover gaskets, cleaned throttle body, flushed the radiator, etc.

Just parked it until I had a little time to look into it more but found out today my wife may need to drive the van to texas to pick some stuff up, so I need to figure this out.
I have no idea how to remedy the fuel trim situation. It may take an expensive high tech scanner and a knowledgable tech to do that.

I usually do all the work on my vehicles myself but this one is completely out of my knowledge level.

Any help would be appreciated by some of you more experienced guys.
 

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2006 Odyssey EX 268,000 miles
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Discussion Starter · #4 ·
thanks for your response. I didn't mean to suggest that a bad cat would cause fuel trim issues but that a rich fuel trim would cause your cat to stop up. At least that is the way I understand it. I think you might be on to something here though as far as possibly my cat code might go away if I have the trim mixture adjusted. I will look into this. many thanks
 

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I am no expert, but I believe your computer adjusts the fuel trims based on other inputs, so you may have some issue like a vacuum leak or a malfunctioning O2 sensor that is causing the fuel trims to be rich. I am not aware that the trims can be "adjusted" other than actually changing the algorithm programming in the computer.
 
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2006 Odyssey EX 268,000 miles
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Discussion Starter · #6 ·
Well that is interesting, I will have to research that. As mentioned I did replace all O2 sensors in 2020 so I am thinking that the cause then must be something else. Also I replaced all the fuel injectors as well as plugs. So I can't imagine what could be causing the cat issue or a problem with fuel trims.
 

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2006 Odyssey EX 268,000 miles
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Discussion Starter · #9 · (Edited)
My 06 Ody threw the codes for O2 sensors because of leaking valve spool assembly ,oil would coat O2 sensor throwing code. No O2 codes since valve spool replaced.
Good find on that. I replaced the gaskets on my Vtec oil housing assembly on my 2006 also in 2020. I am not throwing any O2 sensor codes at this point. My OCD takes over on oil leaks. I fix them as soon as I become aware of them. I just had to do the rear main seal also in 2020. Replaced also oil pan gasket and valve cover gaskets in 2020. In fact I have put a lot of work and money in 2019-2020 getting everything in top shape on this van.

Replaced timing belt in 2019, water pump, tensioners and pulleys, belts, wires, plugs, motor mount at the same time and as mentioned I did replace all fuel injectors and O2 sensors also. Replaced the PCV valve and cleaned the EGR valve and intake.

Now I am about to replace the MICU brain/junction box in the rear of the van that controls the AC, sliding doors, and rear wiper. Had to replace the temperature actuator a couple of months ago under the dash. 2019 also completely rebuilt the front suspension and replaced front struts and rear shocks as well. Blah blah blah. Was hoping to get another 75-100 k out of this van.

I have 2 other cars but it is my favorite because it is so comfortable and has so much room. My 4x4 Tacoma is a beast with a 6" lift and 4.88 gears so it drinks gas like a hog. I use it for hauling equipment and a trailer. My wife drives the 2016 Avalon but I think the Odyssey is more comfortable than the Avalon.

It is very frustrating to now start throwing this code. There aren't really any good mechanics in our area that I trust and the dealer is about 1.5 hours away. Of course the dealer would likely be my last ditch effort anyway.
I don't really want to just replace the CAT without resolving the reason it is going bad.
 

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It's unusual for the cat converter itself to go bad. Were the new O2 sensors you installed NTK or Denso brand?
 
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