Bank 1 runs "lean" after upstream oxygen sensor replacement

nissan
pathfinder

#121

Here is the cat I used for Bank 1: http://www.ebay.com/itm/2005-2009-NISSAN-PATHFINDER-V6-4-0L-FRONT-PASSENGER-SIDE-DIRECT-FIT-CONVERTER-/272479358828?vxp=mtr&hash=item3f71090f6c

Same seller, Bank 2: http://www.ebay.com/itm/2005-2009-NISSAN-PATHFINDER-V6-4-0L-DRIVER-SIDE-FRONT-DIRECT-FIT-CONVERTER-/252700448410?vxp=mtr&hash=item3ad61ed69a

These at the least were of decent weld quality and had good heatshields attached.

Once arrived, cat was of “Shultz” brand, Canada made, all gaskets included, no bolts


#122

Thanks for the help and links.

When I did my B1 CAT R&R I used muffler straps to re secure the heat shield back on by bolting the strap into the old bolt holes then wrapping the straps around available engine hardware, worked very well and somewhat easy to do.

After finding 8 other separate (besides us) people on blog posts describing Nissan PF/Frontier AF Sensors as having baseline readings of 0.3V B1 and 0.6V B2 that indicates to me those are the ECM assigned Voltage values, no one else I have been able to find had any other readings, also I have yet to find someone who knows why this is, all other cars seem to have AF Sensors that have the same Voltage values for both banks?

If I recall you can swap AFS between banks, but cannot swap
O2 sensors because the connectors are different.

Other blog posts:


pathfinder-84-000-miles-ja-let-s.html
Expert: Jared D replied 8 months ago.
Hi,The pa200 isn’t a standard trouble code. They typically start with a P0… I have never seen a pa200 and can’t find one listed in the 2006 pathfinder reference materials. Is it possible that you have any other trouble codes?
Ask Your Own Nissan Question
Customer: replied 8 months ago.
Im sorry its P2A00
Jared D
Expert: Jared D replied 8 months ago.
Oh ok. That makes more sense. That code points to a bad oxygen sensor. The problem is usually in the bank 1 sensor, but sometimes you have to replace both sensors in order to solve the problem. Do you plan to fix it yourself?
Ask Your Own Nissan Question
Jared D
Expert: Jared D replied 8 months ago.
The sensors in question are circled here. Bank 1 sensor 1 and 2 are usually needed when we see the p2a00 code.
Ask Your Own Nissan Question
Jared D
Expert: Jared D replied 8 months ago.
This code can also come on because of exhaust leaks. Do you hear any unusual exhaust noise?

Wiring information needed for A/F sensor change
A long story involving the Wideband A/F Sensor after changing the cat on a 2006 frontier
has boiled down to replacing the current issue Wideband A/F Sensor with the one used on the 2009.

The issue is the 2006 sensor is 5 wires and a 6 pin plug and the 2009 is a 4 pin plug.
The Dealer is no help at all they think they can just plug it in !
Well that wont work. I guess they will figure that one out when they have to do it for a customer.
The one on the left is the 2006 and the one on the right is the 2009

All this is due to a ECM reprogram by the dealer that was supposed to correct a problem of a recurring code for the A/F Sensor after both the cat and the pre and post sensor were replaced on the left side by me not the dealer. The sensors used were Bosch and apparently supposed to be exact OEM replacements.

The Dealer has informed me that I have to now replace both A/F sensors with the one specified as being 226931AA0A which is the same one used on the 2009 model
They wanted $700.00 to do this and for about $200.00 I can do it myself.
Rock auto has agreed to take the original Bosh AF back and credit the cost to new ones which are DENSO 234-9038

Hope someone has been here before or has the information I need to match up the wiring.
I was told this was part of a service bulletin but have not found any info on it other than the reprogramming of the ECM

Thanks!
Attached Thumbnails
Wiring information needed for A/F sensor change-getimage-php-jpg Wiring information needed for A/F sensor change-getimage2-jpg
Last edited by mustang1975; 05-15-2012 at 12:43 PM.

I have a 2006 Pathfinder with ~54K miles on it. Recently the SES light came on and the code pulled was P2A00. OBD2 data scanning showed A/F bank 1 sensor 1 reading of ~0.3V and not changing much. If I raise the RPM to 3-4K range for a few seconds then release the petal completely, it raises the reading to ~0.8V for a short time before returning to ~0.3V. Under the same conditions A/F bank 2 sensor 2 reads ~0.61V rising to ~ 1.3V when rev’d and released, so while it seams that the sensors are doing something, they are clearly not reading the same. I followed all of the code resolution steps in the FSM but I found no problems, so per the FSM I replaced the A/F bank 1 sensor 1 with a new Bosch direct fit sensor. Unfortunately this produced no change in the readings, even after driving the vehicle ~110 stressful highway miles over a mountain pass. I then swapped the old “bad” sensor into the bank 2 sensor 1 slot and what do you know, it reads fine in that slot. I checked the harness for problems the best I could according to the FSM and found nothing so I’m not sure what else is left except the ECM. This is very expensive and so I’d like to be sure before I do this any help would be greatly appreciated.

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User avatarasnorton44
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Re: 2006 Pathfinder P2A00
Postby asnorton44 » Mon May 19, 2014 5:21 pm

Maybe the catalytic converter is bad.

Also, at least for our R50s, the ECU needs a reflash or reprogram of some sort to upgrade the ECU firmware? May apply to your 2006.
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JMPpath
Posts: 3
Joined: Mon May 19, 2014 3:08 pm
Car: 2006 Pathfinder SE off Road
Re: 2006 Pathfinder P2A00
Postby JMPpath » Tue Jun 10, 2014 4:22 pm

Based on the information I’ve seen it doesn’t seem likely that the cat is bad as the primary job of “sensor 2” is to monitor the cat and I have recieved no codes for that. I’ve tried to find out if a reflash is necessary for this truck from the dealer but they seem confused by the question. I told them I replaced the O2 “sensor 1” and asked if I needed a reflash and they asked me what update I wanted, so it did not seem that they were aware of one for this particular model. At this point I have replaced both bank 1 sensor 1 and and bank 2 sensor 1 now but still no change: bank 1 reads ~0.3V and bank 2 still reads ~0.6V. It does not seem to be affected by which specific sensor is in which bank. I have driven hundreds of miles at this point and while the SES light has remained off there is now a recent code pending again (P2A00). I need to take a very long trip (2K miles) at the end of this week and I’m not sure what to try next. I did find a Titan forum with a post with the same problem (0.3V on one side and 0.6V on the other) but they received no response, at least in the forum.
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User avatarTowncivilian
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Re: 2006 Pathfinder P2A00
Postby Towncivilian » Sat Jun 14, 2014 11:36 am

It looks like NTB08-103a - 2007 FRONTIER, PATHFINDER, XTERRA; DTC P0031, P0051, P0133, P0153, P2A00, P2A03, P1148, P1168 would apply to your vehicle, but you have a 2006. I don’t see any other TSBs relating to P2A00, but I’ll check for any more which may have reflashes as part of the procedure.
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JMPpath
Posts: 3
Joined: Mon May 19, 2014 3:08 pm
Car: 2006 Pathfinder SE off Road
Re: 2006 Pathfinder P2A00
Postby JMPpath » Sun Jun 15, 2014 8:06 am

Thanks, I had not seen that one, probably since it is listed under 2007. I will check my old sensors to see which ones I have and talk to my dealer to see if they think this may also be a problem on mine. Somehow I doubt they will want to do the reprogram on a 2006 when the TSB says 2007, they will probably be afraid that it will not be compatible and may cause more problems but I will see.


#123

Originally Posted by mustang1975 View Post
A long story involving the Wideband A/F Sensor after changing the cat on a 2006 frontier
has boiled down to replacing the current issue Wideband A/F Sensor with the one used on the 2009.

The issue is the 2006 sensor is 5 wires and a 6 pin plug and the 2009 is a 4 pin plug.
The Dealer is no help at all they think they can just plug it in !
Well that wont work. I guess they will figure that one out when they have to do it for a customer.
The one on the left is the 2006 and the one on the right is the 2009

All this is due to a ECM reprogram by the dealer that was supposed to correct a problem of a recurring code for the A/F Sensor after both the cat and the pre and post sensor were replaced on the left side by me not the dealer. The sensors used were Bosch and apparently supposed to be exact OEM replacements.

The Dealer has informed me that I have to now replace both A/F sensors with the one specified as being 226931AA0A which is the same one used on the 2009 model
They wanted $700.00 to do this and for about $200.00 I can do it myself.
Rock auto has agreed to take the original Bosh AF back and credit the cost to new ones which are DENSO 234-9038

Hope someone has been here before or has the information I need to match up the wiring.
I was told this was part of a service bulletin but have not found any info on it other than the reprogramming of the ECM

Thanks!
The sensor you need is the one in the picture on the right. The other sensor will not work on your truck. I have done several of these with no problems. Check your front exhaust tubes for leaks. They usually leak at the welds at the connection to the cat. That will cause an a/f sensor code.


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#124

http://x.nissanhelp.com/forums/attachments/frontier-hb-truck/3027d1337109746-wiring-information-needed-f-sensor-change-getimage-php-jpg.att


#125

http://x.nissanhelp.com/forums/frontier-hb-truck/22113-wiring-information-needed-f-sensor-change.html

Try this one for picture of AFS


#126

Here are downstream sensors from NGK/NTK, you can not find “more standard than that”:

right: http://www.rockauto.com/en/moreinfo.php?pk=1644052&cc=1433013&jsn=371
left: http://www.rockauto.com/en/moreinfo.php?pk=1644058&cc=1433013&jsn=379

same from DELPHI:

http://www.rockauto.com/en/moreinfo.php?pk=1323032&cc=1433013&jsn=370
http://www.rockauto.com/en/moreinfo.php?pk=1323995&cc=1433013&jsn=365

you are right, connectors are DIFFERENT :frowning:

I managed to order aftermarket sensors not paying close attention to that, not sure if I can simply re-insert wires/contacts into connectors from my old sensors


#127

on another thought, they looks to be very close, so likely I can simply cut one key on the side of the one which will not fit (driver side) as wires are likely the same

anyway, too late to cancel the order and I have 60 days to return if they are way off


#128

two interesting links on the topic:


to boil it down:

  • this engine does not like non-NGK spark plugs
  • this engine does not like regular grade gas at winter, as it has more oxygenates than in summer
  • obviously, it does not like missing gaskets between exhaust manifold and cat :slight_smile:

so far I’m a little bit doubtful about spark plugs, but $36 is not much to get an Irridium NGK set from RockAuto

gas grade is an interesting thing… my problem really coincided with season switch on gas stations and it takes around 150-250 miles to show up… engine runs great and passes all emission self-tests over 40-50 miles, so the problem shows up way slower than it would do for severe leak or bad sensor or such

what Jay from JustAnswer suggests is to switch to Premium as it does not get oxygenates added, and probably it is the fastest to check

not sure if “0.3 V / 0.6V” thing is a non-issue and only gets me rolling on the wrong trail?


#129

I do not blame you, it is confusing about the AFS voltage, especial since these Nissan’s have been around over a decade and no one has posted anything that explains it.

Maybe it has to do with the shape of the exhaust pipe, you would think B2 would get more back pressure because of the 45 degree turn in the pipe vs B1 with its straight line to the muffler?


#130

yeh, voltage seems to be a dead end

I found some interesting info on my P2A00 code on JustAnswer actually

from what their Nissan expert says, ECM is actually using both S1 and S2 when controlling A/F/ mix, where S2 may be a backup for the situation when S1 is dead

now, I do know for sure I have a leak after cat#1 and before cat#2: it is a small hole in welding, but I was not even considering it to be a problem since it is past S1 sensor, so I through not to make any difference for the closed loop control

apparently, S2 might “condemn” S1 based on the fact that it senses traces of oxygen coming through the leak, throwing P2A00

it is a good day outside tomorrow, so I’m removing cat-1 and will try to either replace it via warranty or fix with high-temp putty (claims 2000 degrees), as this finally looks to be a plausible explanation to my issue

I’m still waiting for my ECM from R&R, it should get to my place only a day after tomorrow


#131

Good luck with the fix


#132

#133

Here it comes: bad weld-spot on catalyst itself!

other than that, I found a leak on the flange between first and second converters

I had a new gasket, but probably it did not attach well since angle of new part was slightly off

these guys from eBay stood behind it and offered refund or replacement on my choice

I go refund and look for other good upstream cat for passenger side

If I find nothing better, I can still go to the same guys, but this time will test with a shop-vac before putting it on :slight_smile:


#134

Good trouble shooting, that might be your cause, just enough to cause a code and difficult to find.


#135

The O2 spacer did not work, although it delayed the code from being set. Will R&R CAT.


#136

pity you did not get an easy “delay-fix”

you replaced one on another bank before, so hopefully it will be way easier on the second bank

for myself, I’ve purchased this one: https://www.amazon.com/Pacesetter-201082-Catalytic-Converter-Pathfinder/dp/B00C6Y7FPG/ref=sr_1_2?ie=UTF8&qid=1483577934&sr=8-2&keywords=Pacesetter+Direct+Fit+Catalytic+Converter+nissan+pathfinder+2006

your driver side is https://www.amazon.com/Pacesetter-201078-Catalytic-Converter-Pathfinder/dp/B00C6Y7G5A/ref=sr_1_1?ie=UTF8&qid=1483577934&sr=8-1&keywords=Pacesetter+Direct+Fit+Catalytic+Converter+nissan+pathfinder+2006

it appears to be USA-made and has 25K miles warranty on cat and 50K warranty on housing (stainless!)

unfortunately Amazon ran out of them, I bought the last one :slight_smile:

eBay to the rescue: http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.XPacesetter+201078.TRS0&_nkw=Pacesetter+201078&_sacat=0


#137

Sound like you are on top if it. Excellent work getting that fast idle problem solved btw. Fast idle problems are often difficult to diagnose and fix.


#138

received my upstream catalyst today

build quality is very good, made “shop-vac test”: 100% solid

as I was attaching it, flange from downstream catalyst FELL OFF, I found substantial fouling around broken weld-seam, so not only I had leaking catalyst itself, but an additional leak developed on the failing weld-seam where it attached to the downstream one

sure enough, seam was failing in the top side of flange initially, so I did not see this black mark during visual inspection

finally, it explains it all: having such a HUGE leak, it is no wonder I was getting P2A00

ordered https://www.amazon.com/gp/product/B0160YR4BM/ref=od_aui_detailpages01?ie=UTF8&psc=1 as their build quality seems to be very good, waiting for a good weather mid next week to finally get it all assembled


#139

Congrats on sticking with it, & getting to the bottom of this pesky problem. It’s a pretty common thing we hear here from posters that when the problem is found, it turned out to be pretty obvious by visual inspection. But it couldn’t be readily visualized until a lot of other stuff was taken apart first.

btw, any chance the old cat is actually ok and still servicable? If so, keep it as a spare.


#140

I’ve filed for a return/refund already, they agreed to take it back, waiting for RMA#

probably it might even work for some time, but it would eventually burn-through given it is right where hot gasses go out of catalyst comb zone