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cat converter wiring

799 Views 37 Replies 5 Participants Last post by  max122756
Help. I had to replace the cat converter on an 03 ex, v6 one cat, the 02 sensor now shows fault when it was removed they cut the o2 wiring off at the snap plugs. Ok the blk and gray is no issue to connect wire to wire but the two whites do they have a certain connection to sensor I keep getting 141 fault code and need help with this. Is there a way to get the harness from the snap plug near the ac inlet all the way to the cat snap plug to insure I have proper connections? thanks
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Help. I had to replace the cat converter on an 03 ex, v6 one cat, the 02 sensor now shows fault when it was removed they cut the o2 wiring off at the snap plugs. Ok the blk and gray is no issue to connect wire to wire but the two whites do they have a certain connection to sensor I keep getting 141 fault code and need help with this. Is there a way to get the harness from the snap plug near the ac inlet all the way to the cat snap plug to insure I have proper connections? thanks
Hi, the black wire is single back to the PCM, Grey is ground, the two whites are for heater circuit, it doesn't matter which way they go. However the schematic for a 2003 shows the following, the first wire combination will be the harness color followed by the corresponding O2 sensor with "universal color of black, grey, white, and white) With the 03 model

On the 3 way converter (upstream)

Black/White = White wires on the sensor that goes back to the PCM.
Black/Yellow = The other white wire, it is the 12v+ feed from fuse #6 driver side fuse box, so if you use a test light and get power that's it
Red/White = Black wire voltage from the PCM
Green/Yellow = Gray (another ground)

On the exhaust pipe (downstream)

Black/Yellow =Black on sensor wire again to fuse 6
Black/White = Black on sensor (orient these black wires in the same connector pin spot on the converter)
White = White back to the PCM
Light Green = Green/Yellow (another ground)
 

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03 pilot since new, 2021 passport Shhhh!! Its a Pilot with no third seating tell no one!!
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Discussion Starter · #6 ·
Ok cat was snatched they cut wiring from harness to cat before snap plugs, see it now??? thanks
 

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Another thing to look at is the wires right at the sensor. I had a fault after installing the cat I took from one vehicle to another. I dragged the cat, but didn't realize I dragged it right on the O2 sensor and exposed the wires enough for them to oxidize and rust through a couple wires. I had to replace the sensor since it was oxidized right at the sensor.
 

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Discussion Starter · #9 ·
Ok I used a bosch connector with a ebay cheapee o2 sensor, I keep getting 141 fault I understand there are two 02 sensors one on manifold one on cat which is bank1 sensor 2? that is the cat correct
 

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Discussion Starter · #10 ·
can it also be a crap 02 sensor from the bay? any brands i should look for known to work with few problems? Should I soilder my connect pts and us heat shrink instead of a term block??
 

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I would go Denso, but NTK works as well. I wouldn't go any other. Honda sells you Denso. Shop around for the cheapest at any reputable auto parts store. Not ebay. Don't cheap out on something like plugs, coils, or sensors. Good rule of thumb is if it is electrical go OEM. This includes Denso O2 sensors and NGK spark plugs. Which is what is used new from Honda. Another thing to keep in mind. Japanese parts for your Japanese vehicle.
 

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Soldering depends on if you are good at soldering. Otherwise I would get non insulated terminals with heat shrink. I would put a large heat shrink on all 4 wires, followed by small heat shrink on each wire. Connect your wires, heat shrink each individual wire, and finish with heat shrink over all wires. Make sure to place your heat shrink first. Sucks forgetting the heat shrink after you connect the wires, and having no way to get the heat shrink on after.
 

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I wouldn't trust Ebay. Especially if it is cheap. Too many knockoffs. I would look at any reputable auto parts store. Not Ebay. Especially for sensors, plugs, coils, or timing belt/kits. Never. Unless you actually get a reputable seller that you know for certain you can trust.
 

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Discussion Starter · #19 ·
Ok got it I ordered a denso off the bay should be here this week, I had issues ohh say 10 years ago same car and had to got thru I believe 2-3 o2 sensors before one would interact with OBC, it is one cat one sensor. thanks. I will keep this going after the repair,
 

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