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Discussion Starter #1
Hello,

Just got this error code. I am going to try Cataclean to see if it can clean the CAT enough to clear the code. Used a bluetooth OBD2 reader and Car Scanner for Android. Anything I can check for to see if it is the 02 sensors and not the cats?

Jay
 

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Before doing anything just reset the error with your OBD2 reader and see if it comes back. If it doesn't, the margin of error is so thin, it's not trigging it anymore, or it could have been just bad fuel (happened for me).
 

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+1 for reset first. Very common for the Cat to be borderline and trigger the code on occasion. Mine would come on then go back off by itself and eventually I broke down and did the non-fouler hack. P0420 has not been back since and that was 1,500 miles ago. Fairly unlikely that it is the O2 sensor itself as that typically triggers a different code(s) like P0134, P0137, or P0141 when the sensor is failing.
 

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Discussion Starter #4
I reset the code. The O2 sensor primary bank in the scanner shows 0 mV and sometimes -0.0xx mV. All the other O2 sensors are above 0.6mV. don't know if it means anything but 20 miles in and it's not back. Bought the cataclean so next fill up I will pop into the tank.

Sent from my SM-G975U using Tapatalk
 

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Discussion Starter #6
I'll wait 500 miles before I thank you myself ;). Any thoughts on the o2 sensor readings that I got from the OBD scanner?
 

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Discussion Starter #9
Interesting so my bank 1 sensor 1 is not normal. What app are you using on the iphone by the way? Much cleaner than mine on Android.
 

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Discussion Starter #11
Well after driving around for an hour running errands with the OBD scanner on it seems both upstream sensors measure about the same thing from -0.3 all the way up to 4 mV when coming off the gas while most of the time averaging 0.03 mV. Downstream sensors stay pretty solid at 0.75 mV. Seems to be working fine.
 

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So as long as the sensor is functioning correctly you could opt to do the non-fouler hack, especially if you live in an area that doesn't smog test though there are reports of cars still passing. These converters are notorious for flowing fine, but failing to clean up the exhaust enough to meet the threshold parameters. I unscrewed my sensor and stacked two of the non-fouler fittings (one drilled out to 1/2" diameter) then put the sensor back in. It's been 1,500 miles and no CEL.
 

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I have been receiving the “check emission system” warning for a couple of months now. I checked through the Nav system and it is the P0420 code. Mine comes on and goes off periodically. I’m sure it’s the bank 1 cat. My MDX is a 2007 in great shape with 150k on the odometer. I would like to keep it for 2 more years. Should I get the cat replaced - try cataclean - or just live with it. I also have noticed a slight drop in MPG from around 20 to 17.5 or so. Otherwise runs well. Any input or advice is appreciated.
 

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My daughter's (High School car) Integra kept getting the P420 code. When she said that the check engine light was back on, I showed her how to use the OBD2 scanner.

When the P420 code came up, I told her that it meant that someone had been smoking weed in this car. Her eyes got BIG.

Ultimately, I used an angled O2 adapter like this one...Mine was made of stainless steel, for $25
 

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Ok that’s a response any kid should get bug eyed about. Lol. When you put this on the integra, did you have to make any modifications? Additionally, how does this affect the Cat? As it is still not functioning correctly, won’t the performance of the car ultimately suffer - not only with poor gas mileage but other issues as well?
 

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Discussion Starter #17

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I would recommend you replace the cat... To avoid more hassle. How long does the vehicle go before indicating the DTC? If it is able to complete readiness testing without acknowledging the failure, in theory you could still pass an emissions test. Any check engine light would prevent an OB2 compliant vehicle from passing though so it is imperative that it completes readiness testing. I have a slight exhaust leak on my 05 at the rear cat to J pipe flange. Under the right conditions, it will set a light every time (WOT in colder weather without lifting for the 1-2 or 2-3 shift). perhaps try to monitor driving and climate conditions at the time the light sets to avoid the message?
 

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Ok that’s a response any kid should get bug eyed about. Lol. When you put this on the integra, did you have to make any modifications? Additionally, how does this affect the Cat? As it is still not functioning correctly, won’t the performance of the car ultimately suffer - not only with poor gas mileage but other issues as well?
I took off the clogged cat and gutted it. I installed the angled O2 sensor at the secondary (downstream) location, I re-installed the gutted cat. No more check engine light and no more bad MPG, but it wouldn't pass emissions.

I put a used (working) cat on and the car passed emissions, but that cat eventually clogged up and I was back to the CEL and bad MPG. The ECU recognizes the extra oil being burned and tries to correct it, by allowing more fuel in to the mix and the MPG is effected.
I couldn't leave the modified O2 adapter on, because it would fail the visual emission inspection. I didn't want to stink up the air, so I got a used engine.

I checked with several shops in the mid-west and they wanted between $2,500 - 3,300 to do a ring job and valve seal replacement.
The Integra had been burning oil and its MPG was down to 19. Burning 1.25 qts per 1000 miles (at about 120,000 miles) kept fouling my cat.

In 2012, I decided to buy a used engine from hmotorsonline dot com (Steve), for $900 shipped. It was the JDM version B18B instead of my USDM B18B1.
Thru Facebook, I found a guy to move all of the USDM sensors/oil pump/brackets/ intake/etc over, change the timing belt, and then install it for $500. All of the new parts that I had to buy were $600, so the total cost was around $2,000.

That solved my issues. Since 2012, the car has been driven 25,000 miles, gets 27 MPG, is emissions legal, and mainly has been sitting in my garage.
 

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Thanks for the reply Carpayment4life. My state does not have emissions. My check emission light comes and goes. I got my MPG up to 21.3 which seems pretty good for this car so I don’t think the cat is completely clogged. Like I said I plan to keep the X for a couple more years and at this point I am going to ride it out. My local Honda/Acura shop told me to drive it until performance suffers and then would need to replace cat. I’m just wondering if I’m keeping for two years - why not just replace cat and not have to deal with CEL all the time. Any thoughts?
 
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