2010 Nissan Sentra - P0420

Reply

  #1  
Old 05-22-18, 10:10 PM
Member
Thread Starter
Join Date: Jul 2017
Location: United States
Posts: 9
2010 Nissan Sentra - P0420

My Sentra threw the infamous P0420 code a few weeks ago. It cleared within a day or two, but now it's back (2 weeks later). I've read that this could indicate my catalytic converter is failing. Before going to a shop, who will want to replace the O2 sensor and cat FIRST, I'm hoping to try some simple fixes on my own. I'm just not sure the best way to go about it. I'm hoping for some assistance on what I could do to try and find the cause of this code.

It's a 2010 Nissan Sentra w/ 135k miles. I'm the original owner. It seems to be running normally...isn't sluggish. I haven't noticed any smoke or heard anything that sounds like an exhaust leak. So, today, I filled my tank with 93, dumped a bottle of Seafoam motor treatment into the tank and ordered some new spark plugs. Is there anything else I could do to try and find the issue on my own?

Thanks.
 
Sponsored Links
  #2  
Old 05-23-18, 04:52 AM
the_tow_guy's Avatar
Group Moderator
Join Date: Feb 2001
Location: SW Fla USA
Posts: 11,531
Well, first off, you could have skipped the 93 octane gas, you're just falling for the oil companies' advertising hype. The extra octane will get you "0".

Do you have a scanner with real-time data capability?

Chances of it being the cat itself are pretty low IMHO. So, first off, I would wait and see if the code repeats. After that I would go ahead and change out the O2's. No need to use OEM, plenty of aftermarket ones that will work fine, I usually buy the Bosch.
 
  #3  
Old 05-23-18, 05:41 AM
Member
Join Date: Jan 2010
Location: North East Kingdom of Vermont
Posts: 2,286
The OBDTC P0420 means that your Catalytic Converter is no longer cleaning your exhaust gases well enough to protect the rest of us . . . . or pass the typical smog test.

It rarely has anything to do with how well your engine is running; but indicates that the catalytic metals inside your converter have become coated with additive deposits and can't convert the gases that are passing by them.

For the past 8 or 9 years, I have cleared my P0420 Codes on a 2002 Volvo S60 by periodically burning a small amount of Lacquer Thinner; but this MUST BE DONE VERY CAREFULLY; otherwise you could blow a head gasket or worse ! This same vehicle is now at 296,000 miles and I'm still running the original Catalytic Converter.

There are expensive products on the market designed for this purpose, like CataClean®; but I have concluded that their primary ingredient is still lacquer thinner and for liability reasons alone, they take a less aggressive approach than I've found necessary to clean the metal honeycomb inside the Converter.

I've written up my approach to dealing with the P0420 Code elsewhere on this Forum . . . . it's not for everyone.

PS: If an Upstream or downstream CO Sensor has failed, it will generate a separate DTC Code; not the P0420.
 
  #4  
Old 05-24-18, 07:00 PM
Member
Thread Starter
Join Date: Jul 2017
Location: United States
Posts: 9
Thanks for the responses...
tow_guy, I bought a “Kitbest Car WiFi OBD OBD2 Scan Tool” and it just arrived. Maybe there’s a test I can run with this? I had an obd2 to 9-pin aerial converter that I used on my older Toyota some time ago. I recall there being an O2 sensor graphing tool. Maybe this new obd tool can do something like that again?
 
  #5  
Old 05-25-18, 05:12 AM
the_tow_guy's Avatar
Group Moderator
Join Date: Feb 2001
Location: SW Fla USA
Posts: 11,531
Well, you can look at the live data that the sensor is providing, but it's a bit hard to read because it's a cycling/fluctuating reading. Most obvious would be if the reading is "stuck" at a particular value or with readings in a range far outside the norm.

Read the article here:

https://axleaddict.com/auto-repair/H...-Oxygen-Sensor

Go to the section on "Reading the Oxygen Sensor’s Signals".

Do a look up on all the various data elements so you will have a benchmark to look for from any of the other sensors, related or not.

If you're willing to experiment, then you could certainly try Vermont's method, although I'm always a little leery of introducing foreign substances into the fuel system other than commercial products like the Seafoam. I bow to his prior experience as I've never tried his method.
 
  #6  
Old 05-25-18, 05:14 AM
the_tow_guy's Avatar
Group Moderator
Join Date: Feb 2001
Location: SW Fla USA
Posts: 11,531
  #7  
Old 05-25-18, 08:57 AM
Member
Join Date: May 2018
Location: United States
Posts: 2
Another method cheap method to determine if its the sensor or the catalytic would be to install Dorman 42009 from an auto parts store. In the video below, he will explain that you will need to drill one of the spacers with a 1/2" drill bit. This is only recommended to verify if the o2 sensor is bad or if the cat is bad. If the code goes away, then you know that your cat will need to be replaced. If the code continues, then the o2 sensor will need to be replaced. Remember, this is for testing purposes only. I would not recommend leaving the spacers installed permanently.

https://www.youtube.com/watch?v=kzm52m0AWSQ
 
  #8  
Old 05-25-18, 11:18 AM
Member
Join Date: Jan 2010
Location: North East Kingdom of Vermont
Posts: 2,286
The P0420 indicates that the Car's Computer is receiving a proper reading from the Upstream Oxygen Sensor AND a proper reading from the Downstream Oxygen Sensor.

In comparing those 2 readings, the Car is telling you that the Catalytic Converter is not effectively reducing the noxious fumes . . . . for whatever reason.

You'd only get the P0420 if the Sensors are performing their function properly but the resulting calculation indicates the Converter isn't producing a clean result.

By the way, Sensors are not serviceable; they do contain some Zirconium Diamonds (making them expensive) and rely on some high tinsel strength springs which do suffer fatigue after a hundred thousand miles or so.

I mentioned that my Volvo is now at 296,000 miles and using the original Catalytic Converter; but the Downstream Sensor failed at about 140,000 miles and the UpStream Sensor gave up the ghost at about 225,000. I guess they don't owe me anything.

Your new Code Reader may help you diagnose your issues; but it cant't fix the problem. My Code Reader will turn off the Check Engine Light; and that got me through a couple years worth of Smog Tests . . . . but now the State has clamped down and that technique no longer works here in Vermont. We now have to actually make sure the Catalytic Converter is actually working and the car's computer doesn't indicate that the Trouble Codes have recently been cleared !

PS: If a Oxygen Sensor is failing to provide a reading to the Car's Computer for calculation, then you'd get a different Diagnostic Code . . . . like a P0131 or P0141 or something else related depending on your specific vehicle,
 

Last edited by Vermont; 05-25-18 at 12:15 PM. Reason: Added Post Script
  #9  
Old 05-28-18, 07:19 AM
Member
Join Date: Jun 2013
Location: usa
Posts: 103
P0420

Could be exhaust leak can cause this Also oil contamination from oil burning Also cats don't go bad they are murdered. If cat is bad make sure fuel trims good at all engine cell loads Don't waste money on 02 sensors. If your scan has graphing capabilities could do a oxygen storage capacity test by graphing pre and post cat 02 sensors and doing some snap throttle tests And monitoring the offset. I use a lab scope Have used a scan tool before. Have to eliminate unnecessary data pids to increase update rate Could send you information on this process if your scan tool has graphing capability
 

Last edited by autojoe; 05-28-18 at 07:49 AM.
  #10  
Old 05-30-18, 09:28 AM
Member
Thread Starter
Join Date: Jul 2017
Location: United States
Posts: 9
Thanks again to all for providing information & recommendations. So, the CEL went away 3 days ago, but came back 1 day later. It's still on. I haven't performed any of the recommended actions in this thread, yet. I'm currently looking for a good, cheap (or free) iphone/ipad app I can use with my wifi obd2 adapter to run some of the tests mentioned in this thread. It seems the couple of free ones I've tried so far have the O2 sensor testing/graphing capability greyed-out (need to buy license to unlock this). Anyone know of a free app that isn't locked down (open source)?
 
  #11  
Old 06-15-18, 09:11 PM
Member
Thread Starter
Join Date: Jul 2017
Location: United States
Posts: 9
Ok, I've tested a few, free programs that should provide me the capability to read some sensor data (including graphs) and perform some tests. I've read some of the sensor data, but still trying to figure out what normal readings should look like on my Nissan. I read the AxleAddict page, and watched the video (thx tow_guy), but I have "O2S1" and "O2S2" sensors. So, I'm not sure which one I'm supposed to be reading as "the O2 sensor", as with Axle's O2 voltage vs. short term fuel trim % tests. If anyone has some time to recommend some tests (and which sensors to read/graph), I'm game! Meanwhile, I'm still reading some of the links provided earlier.

Oh, by the way, the CEL/P0420 code has come and gone a few times since my last post. Ugh...
 
  #12  
Old 06-15-18, 09:34 PM
Member
Thread Starter
Join Date: Jul 2017
Location: United States
Posts: 9
I'm hoping this info I captured might be helpful. I started the car and let it idle for 10 - 15 mins, then graphed the O2S1 volt. next to the O2S2 volt. (B1). O2S1 stayed between 2.2 and 2.3 volts. O2S2 (B1) stayed very close to .7 volts. The slight fluctuations I saw didn't really drop below .68 or above .72 volts. I have some pictures and video of this info, too. Hope this means something.
 
  #13  
Old 06-17-18, 07:59 AM
Member
Thread Starter
Join Date: Jul 2017
Location: United States
Posts: 9
I apologize for piling on top of my own comments, but I was able to figure out this iPad OBDII app (Car Scanner Pro), and ran a slew of tests. I figured, if I'm lucky, there may still be an interested party or two watching my post.

So, I pasted a link to some of the test results I captured. I condensed them down pretty good, but I'm not 100% sure which tests I should be running. I definitely learned how to use this OBD contraption, though...just not sure how to read the data.

https://goo.gl/gD3jqy

I tried to use purposeful naming schemes for each .pdf...hopefully it's intelligible.

BTW, I'm an IT guy and willing to trade some geek prowess for your time, as well. Thanks in advance for any additional guidance you might have.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
'