P0420, Ive been reading for 2 hours now, still have a question
06-11-2012, 08:40 PM
#1
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P0420, Ive been reading for 2 hours now, still have a question
I just bought my 2000 SE on saturday and after about 170 miles the CEL came on and it was the P0420. I was look at the diagram in the stickies and it says its for 2000 Cali and 2001-2003 All spec cars, well i have a 2000 fed spec.
So how many o2 sensors do I have and which one is it? I know its the rear but i dont know if there are 1 or 2 back there.
The car sat for the last 1.5 years and was barely driven and I can only assume the previous owner used regular gas. I filled it up with premium as soon as i got it. Another thing, the intake piping before the filter is missing the resonator and the bottom is just open and the part that connects to the filter box is broken so I used a bunch of electrical tape to give it a temp fix and i also sealed up the opening that would go to the resonator. I need to go check it to see if it held up after my commute today because i didnt see that till after driving it the first 140 miles or so.
In one of the many post I read about this code is that an air intake leak might cause it, is that a possibility? Also read that someone used premium for the first time and it threw the code too.
The problem is I bought it out of state with tabs that are 1.5 years old so I will need to get emissions test, obd2 plug test, before i can register it here and it wont pass but i only have 15 days from when i bought it to do that so I gotta get it fixed sooner then later.
thanks
So how many o2 sensors do I have and which one is it? I know its the rear but i dont know if there are 1 or 2 back there.
The car sat for the last 1.5 years and was barely driven and I can only assume the previous owner used regular gas. I filled it up with premium as soon as i got it. Another thing, the intake piping before the filter is missing the resonator and the bottom is just open and the part that connects to the filter box is broken so I used a bunch of electrical tape to give it a temp fix and i also sealed up the opening that would go to the resonator. I need to go check it to see if it held up after my commute today because i didnt see that till after driving it the first 140 miles or so.
In one of the many post I read about this code is that an air intake leak might cause it, is that a possibility? Also read that someone used premium for the first time and it threw the code too.
The problem is I bought it out of state with tabs that are 1.5 years old so I will need to get emissions test, obd2 plug test, before i can register it here and it wont pass but i only have 15 days from when i bought it to do that so I gotta get it fixed sooner then later.
thanks
06-11-2012, 10:05 PM
#2
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Location: Maine
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Heres a diagram for you. I think the 1st one is the one you are looking for.
http://nissanhelp.com/diy/maxima/pro...tification.php
http://nissanhelp.com/diy/maxima/pro...tification.php
06-11-2012, 10:14 PM
#3
^^2bros is correct. Your Fed-spec has a total of 3 O2 sensors, one in front of each pre-cat, and the last one behind the main cat.
Fix the intake piping properly and clear the codes. Keep running premium in it, that's good.
If you decide to buy a new O2 sensor, go with Denso or NTK brand, or Bosch is ok too but I personally use NTK in all my cars without issue
Fix the intake piping properly and clear the codes. Keep running premium in it, that's good.
If you decide to buy a new O2 sensor, go with Denso or NTK brand, or Bosch is ok too but I personally use NTK in all my cars without issue
06-14-2012, 03:41 AM
#6
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I believe you will want the "downstream" o2 which, in the diagram I gave you, is to the far right. On your car, if you go underneath from the driver side door, you will see it on the exhaust. I got mine from advance auto and have had no problems with it...I think I got the Bosch brand.
06-14-2012, 07:27 AM
#8
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Upstream sensors are:
DENSO Part # 2343111 (right)
DENSO Part # 2343110 (left)
Downstream:
DENSO Part # 2344324
Cats can get clogged, especially if there is a prolonged maintenance issue(s) with the vehicle. IIRC you bought this with 120k miles or so, suffice it to say the sensors are probably toasty by now anyhow.
O2 sensors ARE a wear item and SHOULD be replaced by this time. Even if they are "working" and not throwing any codes, replacing them almost always yields better drivability and sometimes better MPG.
You can extend wires and use universal Denso and/or NTK sensors with success if you don't want to spend a ton o cash on the direct fit units.
The only issue you may have here is potentially clogged precats which the sensors will not solve. Only a nice Y pipe will
Shop Rock Auto a little bit and take a pic of the intake piping,
DENSO Part # 2343111 (right)
DENSO Part # 2343110 (left)
Downstream:
DENSO Part # 2344324
Cats can get clogged, especially if there is a prolonged maintenance issue(s) with the vehicle. IIRC you bought this with 120k miles or so, suffice it to say the sensors are probably toasty by now anyhow.
O2 sensors ARE a wear item and SHOULD be replaced by this time. Even if they are "working" and not throwing any codes, replacing them almost always yields better drivability and sometimes better MPG.
You can extend wires and use universal Denso and/or NTK sensors with success if you don't want to spend a ton o cash on the direct fit units.
The only issue you may have here is potentially clogged precats which the sensors will not solve. Only a nice Y pipe will
Shop Rock Auto a little bit and take a pic of the intake piping,
06-14-2012, 09:48 PM
#10
Nope.
The beauty of the FED spec that you have, the front O2 sensors are located BEFORE the pre-cats, and the rear is AFTER the main cat. The aftermarket Y pipe makes ZERO difference to the front 2 O2 sensors at all, and since your main cat is still there, the rear o2 still does its job. The rear o2 doesn't even start monitoring until AFTER the car has warmed up, so no worries there.
CALI spec is the one that throws a code.
The beauty of the FED spec that you have, the front O2 sensors are located BEFORE the pre-cats, and the rear is AFTER the main cat. The aftermarket Y pipe makes ZERO difference to the front 2 O2 sensors at all, and since your main cat is still there, the rear o2 still does its job. The rear o2 doesn't even start monitoring until AFTER the car has warmed up, so no worries there.
CALI spec is the one that throws a code.
06-14-2012, 10:10 PM
#11
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Nope.
The beauty of the FED spec that you have, the front O2 sensors are located BEFORE the pre-cats, and the rear is AFTER the main cat. The aftermarket Y pipe makes ZERO difference to the front 2 O2 sensors at all, and since your main cat is still there, the rear o2 still does its job. The rear o2 doesn't even start monitoring until AFTER the car has warmed up, so no worries there.
CALI spec is the one that throws a code.
The beauty of the FED spec that you have, the front O2 sensors are located BEFORE the pre-cats, and the rear is AFTER the main cat. The aftermarket Y pipe makes ZERO difference to the front 2 O2 sensors at all, and since your main cat is still there, the rear o2 still does its job. The rear o2 doesn't even start monitoring until AFTER the car has warmed up, so no worries there.
CALI spec is the one that throws a code.
06-16-2012, 01:36 AM
#13
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OK, so it is not the O2 sensor, I replaced it and code still came back and also it was a bosch that i had pulled off and i can tell the other 2 have been replaced also at some point. So there went $100... I also unplugged the front bank 2 sensor and got a different code. So unless it is the rear after cat o2 sensor which is still considered a bank 1 sensor.
Could my intake not being connected right between the hood intake and the filter box really throw the p0420 code? Also looked for an exhaust leak but it was hard to tell, i am not ruling that out. I know a guy at an exhaust shop i may take it to him and have him look at it.
I am stumped and need to get it fixed fast, any ideas?
Could my intake not being connected right between the hood intake and the filter box really throw the p0420 code? Also looked for an exhaust leak but it was hard to tell, i am not ruling that out. I know a guy at an exhaust shop i may take it to him and have him look at it.
I am stumped and need to get it fixed fast, any ideas?
06-16-2012, 03:38 AM
#14
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You replaced the one marked "HO2S2-B1 rear O2 sensor B1" on the diagram correct?
According to this, intake air leaks can cause the p0420 code. Yes, this is for a 99 but should not be different for a 00.
http://boredmder.com/ecucodes/index....1999&DTC=P0420
According to this, intake air leaks can cause the p0420 code. Yes, this is for a 99 but should not be different for a 00.
http://boredmder.com/ecucodes/index....1999&DTC=P0420
06-16-2012, 09:49 AM
#15
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You replaced the one marked "HO2S2-B1 rear O2 sensor B1" on the diagram correct?
According to this, intake air leaks can cause the p0420 code. Yes, this is for a 99 but should not be different for a 00.
http://boredmder.com/ecucodes/index....1999&DTC=P0420
According to this, intake air leaks can cause the p0420 code. Yes, this is for a 99 but should not be different for a 00.
http://boredmder.com/ecucodes/index....1999&DTC=P0420
Also how can I find an exhaust leak on my own? The only time I've been able to before is because it was cold out and i could see it.
06-16-2012, 01:51 PM
#16
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Well there's your problem, the DOWNSTREAM is also bank 1. I am pretty sure in all the stuff I read, that p0420 refers to the o2 sensor I said in my post #6...the DOWNSTREAM one. Do some googling of your own to be sure though. And yes, the rear WILL throw a code. Not sure who told you it won't but they were misinformed. You most likely will not have driveability issues with a bad rear, but it will throw a code. My bet, like I told you in post #6, replace downstream not the one you did and all will be good.
06-16-2012, 09:08 PM
#17
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After you have replaced all the sensors and the light still does not go out, come back and re-read my reply.
Bottom line:- Either put new OEM pre-cats or get the downstream O2 sensor extension. In 99.9% that is how you fix or mask the P0420/P0430 problems. NOT BY CHANGING O2 SENSORS.
But you have to learn it hard way :-(
Bottom line:- Either put new OEM pre-cats or get the downstream O2 sensor extension. In 99.9% that is how you fix or mask the P0420/P0430 problems. NOT BY CHANGING O2 SENSORS.
But you have to learn it hard way :-(
06-16-2012, 10:43 PM
#18
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After you have replaced all the sensors and the light still does not go out, come back and re-read my reply.
Bottom line:- Either put new OEM pre-cats or get the downstream O2 sensor extension. In 99.9% that is how you fix or mask the P0420/P0430 problems. NOT BY CHANGING O2 SENSORS.
But you have to learn it hard way :-(
Bottom line:- Either put new OEM pre-cats or get the downstream O2 sensor extension. In 99.9% that is how you fix or mask the P0420/P0430 problems. NOT BY CHANGING O2 SENSORS.
But you have to learn it hard way :-(
I Googled the extension and I don't get it, seems like it is for headers. Does the longer cord make the sensor read differently?
06-17-2012, 07:03 AM
#19
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Here is the explanation
Computer monitors pre-cat's efficiency on our maxima. When the efficiency drops below 95% it triggers P0420 (bank one - firewall) or P0430 (bank two - radiator). The way it does is to compare the cross count of upstream and downstream sensor. If downstream sensor is switching at similar rate under the specified conditions, computer deduces that the converter is not doing its job. The problem is it is way stricter than necessary. If you have O2 sensor failure, you will get specific O2 code. A weak or dead post-cat sensor will actually switch lazily and thus would be able to fool the computer in to thinking that your cat is still good. A O2 sensor extension (go to ebay) moves the POST-CAT sensor just slightly away from the flow of the exhaust. This cuts down on the activity seen by that O2 sensor and it switches less. Now the computer is happy and turns off your P0420/P0430 light.
It is extremely tight to get the extension fitted between the sensor and the bung but it is doable. Without a lift and possibly torch, it will be a difficult job.
First thing to do is to get couple of those extensions from ebay. Buy the stainless one, those are only few bucks more and will not rust. Then research here to find exactly where the post-cat sensors are. Unthread the sensor. This is where a good O2 removal socket and a torch to heat it up would be necessary. Count the twist you are putting on the wire as you are taking off that sensor. Put the new extension on the exhaust bung first, tighten it and then put the sensor back on the extension. Make sure that at the end, you have not twisted the cable. Otherwise you can follow the wire and disconnect it completely while doing this work. Just do it for both the post-cat sensor. Almost everybody has CA emission Maxima whether you are in CA or not.
As I said before this fakes your computer. Real repair involves replacing those pre-cats with the OEM ones. Aftermarket will trigger the code back in few months as they are not as efficient as the OEM.
IF YOUR PRECATS ARE DISINTEGRATED, THEN PLEASE CHANGE THEM AS WE HAVE HEARD OF CASES WHERE IT SUCKS THE CONTENT THROUGH THE EXHAUST VALVE (DON'T ASK ME HOW!) AND DESTROYS THE ENGINE.
Computer monitors pre-cat's efficiency on our maxima. When the efficiency drops below 95% it triggers P0420 (bank one - firewall) or P0430 (bank two - radiator). The way it does is to compare the cross count of upstream and downstream sensor. If downstream sensor is switching at similar rate under the specified conditions, computer deduces that the converter is not doing its job. The problem is it is way stricter than necessary. If you have O2 sensor failure, you will get specific O2 code. A weak or dead post-cat sensor will actually switch lazily and thus would be able to fool the computer in to thinking that your cat is still good. A O2 sensor extension (go to ebay) moves the POST-CAT sensor just slightly away from the flow of the exhaust. This cuts down on the activity seen by that O2 sensor and it switches less. Now the computer is happy and turns off your P0420/P0430 light.
It is extremely tight to get the extension fitted between the sensor and the bung but it is doable. Without a lift and possibly torch, it will be a difficult job.
First thing to do is to get couple of those extensions from ebay. Buy the stainless one, those are only few bucks more and will not rust. Then research here to find exactly where the post-cat sensors are. Unthread the sensor. This is where a good O2 removal socket and a torch to heat it up would be necessary. Count the twist you are putting on the wire as you are taking off that sensor. Put the new extension on the exhaust bung first, tighten it and then put the sensor back on the extension. Make sure that at the end, you have not twisted the cable. Otherwise you can follow the wire and disconnect it completely while doing this work. Just do it for both the post-cat sensor. Almost everybody has CA emission Maxima whether you are in CA or not.
As I said before this fakes your computer. Real repair involves replacing those pre-cats with the OEM ones. Aftermarket will trigger the code back in few months as they are not as efficient as the OEM.
IF YOUR PRECATS ARE DISINTEGRATED, THEN PLEASE CHANGE THEM AS WE HAVE HEARD OF CASES WHERE IT SUCKS THE CONTENT THROUGH THE EXHAUST VALVE (DON'T ASK ME HOW!) AND DESTROYS THE ENGINE.
06-17-2012, 07:09 AM
#20
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How many codes do you have? You *have* to have your own code reader scanner capable of giving you IM status. There is a way to pass the emission if you are only getting the P0420 code if it does not immediately come back. You hook up the scanner essentially every time you drive. If the light is on, reset it and then watch for the IM status. Also during this time, drive like maniac i.e. two pedal full gas or full brake!
The P0420 test is run when you are decelerating from highway speed. If you slamm of the brakes before taking the exit, computer does not have time to do the test. So what you do is the make sure everything except cat monitor is completed by watching the scanner. If that is only thing left, you drive straight to the emission station. You are allowed one waiver.
I have done this twice before finding the O2 sensor extensions.
http://www.ebay.com/sch/i.html?_trks...nsion&_sacat=0
This is what I recommend but the fit would be tight. The short one might not work.
http://www.ebay.com/itm/O2-Oxygen-se...r#ht_500wt_915
Good luck and since you are a dad of few precious little ones, pay more attention to adults of this forum and ignore the advice given to you by all the teenagers :-)
The P0420 test is run when you are decelerating from highway speed. If you slamm of the brakes before taking the exit, computer does not have time to do the test. So what you do is the make sure everything except cat monitor is completed by watching the scanner. If that is only thing left, you drive straight to the emission station. You are allowed one waiver.
I have done this twice before finding the O2 sensor extensions.
http://www.ebay.com/sch/i.html?_trks...nsion&_sacat=0
This is what I recommend but the fit would be tight. The short one might not work.
http://www.ebay.com/itm/O2-Oxygen-se...r#ht_500wt_915
Good luck and since you are a dad of few precious little ones, pay more attention to adults of this forum and ignore the advice given to you by all the teenagers :-)
Last edited by sontakke; 06-17-2012 at 07:16 AM.
06-17-2012, 10:11 AM
#21
No, I replaced the one on the firewall because that was a Bank 1 also and people have said the rear one will not throw a code usually. Also if you get an aftermarket intake doesn't it get rid of the whole intake piping from the grill anyway and just be a open filter behind the battery? That would throw a code too wouldn't it?
Also how can I find an exhaust leak on my own? The only time I've been able to before is because it was cold out and i could see it.
Also how can I find an exhaust leak on my own? The only time I've been able to before is because it was cold out and i could see it.
06-21-2012, 12:29 PM
#23
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Got tired of wasting hours messing with it and in Washington if you fail emissions then spend $150 on diagnosing or fixing it at a certified shop you get a waiver. So that's what I did but I am pretty sure its the precats cuz car doesn't have the power it should and that'd what the p0420 code is for right? So now I can register it and just get a y pipe when I have the money.
06-21-2012, 12:45 PM
#24
read this thread over on NICo club:
http://forums.nicoclub.com/00-i30-p0...d-t512416.html
http://forums.nicoclub.com/00-i30-p0...d-t512416.html
The P0420 problem is most likely the Bank 1 Pre-Cat (below the engine) or the related O2 sensors. You may have SMOG Check issue with the y-pipe so check your state emission requirements.
I almost forgot, there is an Infinti Technical Bulletin that covers P0420. It may involve reprogramming of the ECU (due to mis-diagnosis) OR replacement of the Pre-Cat and front O2 sensor, depending on the part number of the ECM. Refer to the link below.
http://ww2.justanswer.com/uploads/badda ... 0-054b.pdf
You have a 10-year old car and parts will likely fail as time goes by. A lot of components are rated @ 100K miles - plugs, O2 sensors, etc. Even Federal Emission warranty is only for 8 years/80K miles. Suspension components are typically replaced @ 60-90K miles.
The Maxima/I30 have better than average reliability. So as long they are properly maintained, they should last beyond the current average lifespan of 12 years/128K miles.
So you have had Bank 2 Pre-Cat (P0430) replaced last year and this time you have P0420 (Bank 1 Pre-Cat). Bank 1 refers to Cylinders 1-3-5 (close to the firewall) while Bank 2 is for Cylinders 2-4-6 (front of the engine, towards radiator). Bank 2 Pre-Cat is visible from the front of the engine while with Bank 1 Pre-Cat, you have to safely jack up the car (pax side) as it is under the engine.
The 3-way Pre-Cat and Main Cat, aside from oxidizing/reducing harmful CO, HC and NOx into less harmful gases, also store oxygen. In the 00 I30, each Pre-Cat has a front (upstream) and rear (downstream) O2 sensors. There is no O2 sensor in the main cat. The ECM controls air-fuel mixture as a function of throttle position, mass air flow, front O2 sensors, etc. Normally. the O2 sensors 'see' air-fuel mixture switching from lean-ideal-rich and so on. Due to to O2 storage capability of the 'cat,' the rear O2 sensors switch slower than the front O2 sensors. But if the Pre-Cat is worn out (unable to store O2), then the rear O2 sensor switch rate approaches the front O2 sensor switch rate. At a certain threshold, the ECM flags a failing 'cat' (low efficiency) and generates the fault code, P0420 or P0430, etc.
From my experience with Nissan/Infiniti cars, 'cats' and O2 sensors go beyond 10 years The first time I replaced an O2 sensor is this year - Bank 2 Rear on a 99 I30 and Bank 2 Front on a 97 Q45. I expect to replace O2 sensors in the coming years but I hope the cat will last the lifetime of the car (knock on wood).
The 'cat' and O2 sensors can fail prematurely due to contamination (oil, silicon, phosphorous, etc), poor quality gas, engine misfire and/or continuous exposure to 'rich' air-fuel mixture. So make sure you don have intake/exhaust leak, your spark plugs are not over 100K miles and the fuel injectors are firing correctly.
I almost forgot, there is an Infinti Technical Bulletin that covers P0420. It may involve reprogramming of the ECU (due to mis-diagnosis) OR replacement of the Pre-Cat and front O2 sensor, depending on the part number of the ECM. Refer to the link below.
http://ww2.justanswer.com/uploads/badda ... 0-054b.pdf
You have a 10-year old car and parts will likely fail as time goes by. A lot of components are rated @ 100K miles - plugs, O2 sensors, etc. Even Federal Emission warranty is only for 8 years/80K miles. Suspension components are typically replaced @ 60-90K miles.
The Maxima/I30 have better than average reliability. So as long they are properly maintained, they should last beyond the current average lifespan of 12 years/128K miles.
So you have had Bank 2 Pre-Cat (P0430) replaced last year and this time you have P0420 (Bank 1 Pre-Cat). Bank 1 refers to Cylinders 1-3-5 (close to the firewall) while Bank 2 is for Cylinders 2-4-6 (front of the engine, towards radiator). Bank 2 Pre-Cat is visible from the front of the engine while with Bank 1 Pre-Cat, you have to safely jack up the car (pax side) as it is under the engine.
The 3-way Pre-Cat and Main Cat, aside from oxidizing/reducing harmful CO, HC and NOx into less harmful gases, also store oxygen. In the 00 I30, each Pre-Cat has a front (upstream) and rear (downstream) O2 sensors. There is no O2 sensor in the main cat. The ECM controls air-fuel mixture as a function of throttle position, mass air flow, front O2 sensors, etc. Normally. the O2 sensors 'see' air-fuel mixture switching from lean-ideal-rich and so on. Due to to O2 storage capability of the 'cat,' the rear O2 sensors switch slower than the front O2 sensors. But if the Pre-Cat is worn out (unable to store O2), then the rear O2 sensor switch rate approaches the front O2 sensor switch rate. At a certain threshold, the ECM flags a failing 'cat' (low efficiency) and generates the fault code, P0420 or P0430, etc.
From my experience with Nissan/Infiniti cars, 'cats' and O2 sensors go beyond 10 years The first time I replaced an O2 sensor is this year - Bank 2 Rear on a 99 I30 and Bank 2 Front on a 97 Q45. I expect to replace O2 sensors in the coming years but I hope the cat will last the lifetime of the car (knock on wood).
The 'cat' and O2 sensors can fail prematurely due to contamination (oil, silicon, phosphorous, etc), poor quality gas, engine misfire and/or continuous exposure to 'rich' air-fuel mixture. So make sure you don have intake/exhaust leak, your spark plugs are not over 100K miles and the fuel injectors are firing correctly.
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