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I had the PO420 code show up is it easy to determine if the code is from the sensor or is the catalytic toast. I have 265,000 km on the 2006 Pilot. Never replaced any of the sensors for O2 yet. Mostly highway driving. Car seems to run well and milage is normal. Any help in trouble shooting would be appreciated.

Anyone know how to remove the connectors off of the mounting bracket would be appreciated.:)
 

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I'll be keeping watch of this post as I too have had a p0420 code pop up. I've cleared it and it hasn't come back on and its been about a month.

I'm 90% sure it will be an o2 sensor problem, but I'm a little unsure of which one. Bank one is the o2 near the firewall, but is it the one before or after the cat is my question.
 

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2007 Pilot with 250,000 kms and i also received the beloved P0420 this winter. I know this is the bank 1 sensor 2, which should be the after cat sensor. i cleared the code, but on really cold (-20C) nights I warm it up and I think this may help cause the code?

I have priced the Cat @ $825 through the dealer and $270 for each sensor. OUCH! I am looking for other options, custom exhaust with aftermarket CATs and maybe the spark non-fouler trick are my options so far. Any ideas???
 

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I have priced the Cat @ $825 through the dealer and $270 for each sensor. OUCH! I am looking for other options, custom exhaust with aftermarket CATs and maybe the spark non-fouler trick are my options so far. Any ideas???
I had this error on my wife's Pilot and it turned out that the CAT and 4 O2 sensors needed to be replaced (140,000 miles). An independent shop used the Honda CAT (after-market ones may still throw an error, and after-market O2 sensors that were about half the price of those from Honda.
 

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Hey folks. Same boat here. Wife's car has 135,000 miles and popping a P0420 and P0430 code. I want to change the 02 sensors first before going for the full cats, but I am a little confused. On NGK's website it shows 2 O2 sensors for this car (2005 Pilot). The #24255 Downstream Rear and #24259 Downstream front.
On the Honda Schematics is shows;

Sensor RR, Secondary Oxygen #36542-RKB-004
Sensor, FR Secondary Oxygen #36532-RKB-004
Sensor, FR LAF #36531-RDM-A01
Sensor LAF # 36351-RCA-A02.

Any ideas which one of the NGK's is which?

Thanks in advance!
Semper Fi
 

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A few months back my 06 Pilot threw the same code at 82K miles, which is just beyond the warranty coverage period for the emissions control system so I had to foot the bill.

I bought a genuine Honda cat and had a local Honda mechanic replace it since I just don't have the time, what with little kids and all. Didn't need to replace the O2 sensors and after the new cat the error code went away for good. The mechanic said the bank 1 (rear) cat is a b*tch and it took him about 4~5 hours to do the replacement. Strangely, he said the front cat is even harder to replace which seems counter-intuitive to me but oh well.
 

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Here is the email I got back from NGK
Semper Fi

Honda’s part numbers Vs. NTK’s numbers are as follows:

Sensor RR, Secondary Oxygen part # 36542-RKB-004 crosses into NTK Part # 24255
NGK/NTK 24255 Thimble Type OE Identical Oxygen Sensor.

Sensor, FR Secondary Oxygen #36532-RKB-004 crosses into NTK Part # 24259 NGK/NTK 24259 Thimble Type OE Identical Oxygen Sensor.

Sensor, FR LAF #36531-RDM-A01 crosses into NTK Part # 24302 NGK/NTK 24302 Air Fuel Ratio Sensor.

Sensor LAF # 36351-RCA-A02 is not pulling up in my system as a cross. I am listing a cross for a 36531-RCA-A02 which crosses into NTK Part # 24302 NGK/NTK 24302 Air Fuel Ratio Sensor



You might want to contact your local Honda dealer to confirm that 36531-RCA-A02 is the correct Honda part number. If 36531-RCA-A02 is indeed the right part number you will need: 1qty 24255, 1qty 24259, & 2qty 24302. If you have any further questions feel free to contact us!
 

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PO420, PO430 and Snake Oil

Hi All
Upstream $100 - $140, DownStream $50 - $110 and the CAT $350
Snake Oil, $10 - Seafoam in Gas Tank, Chevron fuel Injection Cleaner in gas tank.
Problems, Clogged fuel injectors, Fuel Pump, Wiring and connectors, bad O2, Bad CAT,
Reference Honda Service News Article Jan 2008
1. Under 80K miles, fix under warrantee, goto dealer ASAP
2. Write Down and Reset Codes, add Seafoam or Chevron fuel Injection Cleaner to gas tank and fill up with Chevron Gas, drive for 400 miles or 1 tank.
3. upstream sensors have 12v heater, check that you have 12v at connector
Replace Two or Four sensors at one time.
4. Still getting codes, Replace the CAT (I would do 3 - 5 tanks with Cheveron Gas and Seafoam in gas tank before I replaced a CAT.
5. Very high mileage cars 175K - 250K you may need to replace four O2 Sensors and the Three CATS. Check Auto wreckers for low mileage wreck with 40K or less.

See O2 Sensor replacement Tips
http://www.piloteers.org/forums/69-2003-2008-pilot/31934-o2-sensor-replacement-tips.html
 

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A food way to test a catalytic converter's performance is to use an infra red thermometer. Run the car to normal operating temp. Raise the idle to 2500 rpm and hold it for 3 minutes. Brian it back down to idle and take a temp reading in front and behind each cat. Temperatures should be significantly hotter coming out of the cat.

If you have access to a scan tool with live data, monitor the millivolt readings between reformat and rear sensors. The rear sensor should be switching slower and reading different numbers than the front sensor. If the front and rear sensors are mirroring each other, it's a pretty good sign you have a bad cat monitor sensor.
 

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add me to this list. it came on 2 weeks ago. got the code read at autozone. added fuel system cleaner and premium gas and it will go off eventually only to come back on after a couple hundred mles.

is it bad if ignore it? i dont plan on replacing the 02 sensors or cats. i dont have emissions tests.
 

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My wife 2006 Pilot EX (4wd) has the same code P0420 but the strange thing is this came out after the dealer did a smog test (due for registration renewal). It passed the smog and we got a certifacte but as soon as she drove out of the dealership 2 lights came out, the VTM-4 and the check engine light.

she immediately drove back to the dealer, the dealer just reset it without checking for any code, then after a week same lights appear, We went back for them to check and this time they told us 2 codes , the PO0420 and PO175. They said we have to replace the CAT and do a valve pressure adjustment, $ 830 + $399.
 

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I also have a 2006 pilot with the check engine light throwing po420 code. I have searched thru this forum & have read tons of postings on the subject. Problem is, im more confused than ever! Some say try replacing O2 sensors before replacing cat, others say the po420 code is specific to the cat & O2 sensors throw a different code. Surely there is a way to confirm the issue & fix it on the first attempt instead of a process of elimination approach. Please help clarify!!!
 

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I also have a 2006 pilot with the check engine light throwing po420 code. I have searched thru this forum & have read tons of postings on the subject. Problem is, im more confused than ever! Some say try replacing O2 sensors before replacing cat, others say the po420 code is specific to the cat & O2 sensors throw a different code. Surely there is a way to confirm the issue & fix it on the first attempt instead of a process of elimination approach. Please help clarify!!!
Austin2U, I have the same problem on my 05 Pilot. I will be changing both O2 Sensors on Bank 1 on Saturday, weather permitting. I'll let you know how I make out.

Does the engine sputter at all, especially over 40mph? Mine does, and it seems to have started at the same time the P0420 came up, and came back again twice quickly after I reset the code.

BB
 

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Beachbum07

I have not noticed any sputter or any negative effect on performance. Runs fine, it's just the check engine light & code that is the issue. Parts & labor are not cheap for either O2's or Cat so I want to make sure Im repairing the right culprit
 

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My CRV has thrown that code a few times (a couple of hundred miles apart.

Put in a set of plugs and a new air filter and has not come on in 3 months (probably 2000 miles)

Not a fix, just figure it is marginal, and any combustion inefficiency is putting it over the edge.
 

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mine goes off/on randomly. doesnt matter what kind of gas or treatments added. the plugs are new. i dont see or feel any adverse effects. im about to fix the cel with tape.
 

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p0420 orp0430 are cat codes not o2 sensor codes
p0420 is bank 1 which is by the firewall
p0430 is bank 2 which in by the radiator
check with your dealers if there are any pcm updates , i know acura released a pcm update regarding these codes for all v6 engines
im not sure honda did as well
 
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