If you have the Muzzler installed and are getting a P0128 then it's likely you're running to high of a resistor. If you don't have the Muzzler installed then you either have a stuck thermostat or a problem in the temp sensor.

For the P2096 and P0420 the problem could be one issue or a couple. You could have a downstream sensor that is going. You could also have an exhaust leak or crack in the exhaust in the catalytic converter neighborhood. I have a Mercedes CLS55 AMG sitting in my driveway right now that has a P2096 code that I found a cracked catalytic converter on.

Start the engine and warm it up. Be sure and get the converters good and warm by running at about 3000 RPM for 2-3 minutes. Let it idle. Plug in your scan tool and bring up the live data. Scroll to Bank 1 Sensor 2 and take a look at the voltage. It should be somewhere between 100mV and 900mV. Compare to the Bank 2 Sensor 2 for a known good. They should be at similar voltages. On a downstream sensor you want it to be somewhere above 450mV and fairly steady with an occasional up or down in voltage but mostly steady. The P2096 code indicates that it's below 450mV for too long. See if you can get it to change voltage by doing some quick snap wide open throttles. Just momentarily put your foot to the floor and let up...just enough to rev the engine but not over-rev it. You should see the sensor go rich or higher voltage, hopefully close to 800mV. If you're not getting any reaction out of the sensor it's likely stuck. To confirm you'd want to check voltage on it directly but that takes more specialized tools. The next best thing is to just unplug the sensor and see if the voltage changes on the scan tool. If it does, I'd probably just replace the sensor. If the voltage doesn't change when unplugged then more diagnosis of a wiring issue might be in order.

The P0420 code really can't be used to confirm a bad cat until the O2 sensor is working properly.

 

Thanks so much for the thorough explanation! I was suspecting the O2 sensor since I received both a too rich (pending code) and the too lean codes, but I'd rather be sure (or close to it) before I buy one.
I brought the tool with me today and plan on logging / graphing the drive home which should tell me a bit. Yesterday before I received my tool, I used a friend's tool and wasn't really sure what I was doing, but I do remember seeing O2B1S2 stuck at 0.000V with intermittent blips higher while O2B2S2 was pretty steady around 0.634V. I hooked up my tool last night and both were in the range you mentioned above, so I hope the logging will show me something.

Thanks again for the help! I'll post what I find.

P.S. The Muzzler was on when the P0128 codes were set. I removed it on 4/2/18 when I cleared the codes. I am using the standard (default) resistor.

 

If you were showing a 0v on that sensor then either there is a wiring issue or the sensor is no good. If you can see some blips when you snap the throttle that pretty much rules out a wiring issue to the PCM and it's likely the sensor is bad.

On your P0128 I'd contact Verbatim and get his input on what to do. I don't know what "standard (default)" means. Usually the blue is used. Is that what you used? He has other resistors he can send you but you have to be clear with what you used.

 

Here is the plotted log I took during a short 1-2 mile drive. The van was warm but in the beginning it still seems that O2B1S2 is not adjusting / jumping as much as O2B2S2. Then near the end they seem closer to each other. I was hoping for something more clear cut but still think if anything that O2B1S2 is going bad. Thoughts?

 

Unless the wiring is damaged (maybe by rodents chewing) I would just take this to the dealer. These codes are emission related and the van has a very long warranty on those parts. Especially ones sold in California. If the van had 162k on it I would encourage your current quest. But at 66k this is not your problem, it’s Honda’s.
Also, if you are using the cheapest gas you can find, try running a few tanks of top tier fuel.

 

The logs/graphs aren't conclusive without some other vehicle data pids to go with it. I'd like to know where the idle cuts are (coasting, no gas) and I'd like to see what the graph looks like under a wide open throttle run (just 1st to 2nd gear--you don't have to exceed the speed limit). Including TPS data would be helpful for that.

From the limited data there, it appears to me the sensor is working. It appears to switch from full rich to full lean. You'll notice that when the Lambda on the front O2's (front O2's are wide band air fuel ratio sensors) goes high, the rear O2's go low which indicates the sensors are reading a lean condition. When the Lambda goes low, the rear O2's go high which indicates rich. Again, without more data I can't say for sure but with the switching up and down of the bank 1 sensor 2, it appears to me the converter is not working and validating the P0420 code. If the converter has failed there's no way I'd replace it without replacing both O2's so at this point I'd probably replace both O2's first, see if it helps any, and then if it doesn't, replace the converter. I've solved P0420 codes with new O2 sensors before so it's not unheard of. The last one I did was on a 2004 Toyota Sienna and reading mode 6 data from the scan tool verified the converter code wasn't going to come back any time soon after the sensor replacement. I'm not suggesting you dive into Mode 6 as it is quite advanced and many professional techs don't even know how use it. The problem could actually be in the upstream sensor, causing the rear sensor to switch like that. Air fuel ratio sensors are extremely difficult to diagnose and sometimes replacement is the only way to rule anything out. You can get NTK sensors on RockAuto for fairly inexpensive and they are the same exact sensor as the OEM.

The other data pid info that would be helpful here is fuel trims. It's important to know why the converter failed so that the replacement doesn't also fail. Also, P2096 is not a Honda code..it's not in the service manual...so there is another code stored in the enhanced data side that would probably shed a bit more light on the failure.

Hope that helps. Taking it to dealer will be a waste of time as they are not going to spend any time diagnosing it. They will just replace the sensors and the converter. If it's still under warranty then that's what I'd do but, if not, and if you can turn wrenches, you can do that yourself and save hundreds and be in the same place when you're done. The converter does have a long warranty in California so it is possible it's still under warranty.

My last note on this would be that poor quality fuel can cause these codes so the suggestion to make sure you're using top tier fuel is a good one.

 

Warranty for 2010 Ody emissions stuff is 7yr/70k whichever comes first.
So no, this wouldn't still be under warranty because it's AGED OUT - not because of miles. (unless it was sitting on the dealer lot, new, for a LOOOOONG time as it would have had to be driven off the lot new AFTER 5/12/2011... not very likely for a 2010)

Since this is going to be your cost, while I would do a physical inspection (mainly to inspect the cat and wiring to the O2 sensors), the data seems to indicate O2B1S2 has an intermittent fault - and that intermittent fault is most likely triggering the code. That is likely either internal or external (wiring). If you thoroughly inspect the leads (from sensor to harness), and find no problems, I'd personally feel comfortable recommending replacing that 02 sensor... It's not very expensive, and it's most likely the source of the problem.

 

... the data seems to indicate O2B1S2 has an intermittent fault - and that intermittent fault is most likely triggering the code. ...

So, what part of the data stream indicates that? I do see some instances where the voltage on B1S2 drops to 0v but they coincide with B2S2 and both of the A/F ratio sensors going full lean (high voltage,) as well. Knowing what the engine was doing during those times is key but I'm guessing a fuel cut, or coasting, since all the sensors indicate lean during those times.

The only thing I see on B1S2 is switching between rich and lean on the downstream sensor which is indicative of a failed cat. I think the converter is not working but it's hard to know for sure without having new sensors in there. They do appear to be working but those A/F ratio sensors are nearly impossible to diagnose for sure.

I would like to see a wide open throttle run and graph what B1S2 does. It should go full rich (high voltage) and stay rich during WOT. If it doesn't then I'd suspect a problem with B1S2 and not a failed cat.

 

Thanks for all the feedback! This is a 2014 purchased in Oct. of 2014 so we still have a bit of time under the emissions warranty. The problem I found is that the O2 sensors aren't covered as the warranty on them ended at 3yrs/50K miles. That seems incredibly stupid to me but that's what it is. Thankfully the Cats are covered for 8yrs/80K miles.

At this point the dealer wants $149 charge for inspection if the problem is found not to be covered, ie O2 sensors. If it turns out to be O2 sensors, they will waive the fee if I have them repair it. However they will charge $150-$220 for each sensor depending on the sensor, plus an installation fee which could run $100-$400 depending on the number of sensors to replace. Seems excessive to me since I could replace them for about $100 and a 1/2 hour of my time each. That said I'd rather not replace parts that aren't required as funds are tight right now.

We do use only Top Tier gas, mainly Costco, but I've read about issues some people with Costco gas even though it is Top Tier. I plan to use something else with the next tank or two but I don't really want this to go on much longer if it could possibly cause other issues.

I just realized that I forgot to post some of the freeze frame data I pulled for the captured codes. When I used my friend's Actron Scanner it had both codes but only showed freeze frame for P2096. Everything seems OK to me other than fuel trims 3 & 4, but I'm not sure what I'm looking at. The freeze frame data is below:

TROUB CODE: P2096
ABSLT TPS %: 34.9
ENG SPEED RPM: 2167
BARO PRS KPA: 101
CALC LOAD %: 100.0
MAF FLOW GR/SE: 57.65
MAP KPA: 93
COOLANT DEG F: 177
IAT DEG F: 73
IGN ADVANCE DE: 7.5
ST FTRM1 %: 0.0
LT FTRM1 %: -3.4
ST FTRM2 %: 0.0
LT FTRM2 %: -4.9
ST FTRM3 %: -33.0
LT FTRM3 %: -33.0
ST FTRM4 %: -33.0
LT FTRM4 %: -33.0
VEH SPEED MPH: 45
ABSLT LOAD: 77.0
FUEL SYS 1: CLSD
FUEL SYS 2: CLSD
REL TPS %: 32.1
THROT CMD %: 34.9
ABS TPS B %: 47.8
ACC POS D %: 39.6
ACC POS E %: 19.6
EGR ERR %: 0.0
EGR COMMAND %: 0.0
EVAP PURGE %: 90.1
CMD EQ RATIO: 1.013
FUEL LEVEL %: 94.5
VPWR V: 13.625
ENG RUN m:s: 32:54

When I checked with my scan tool it only had the P0420 code and freeze frame which was:

Freeze Frame Data for address 711
PID02 DTC that caused freeze frame data storage: P0420
PID03 Fuel system 1/2 status: Closed loop, using O2 sensors
... Closed loop, using O2 sensors
PID04 Calculated load value: 51.0 %
PID05 Engine coolant temperature: 81 °C
PID06 Short Term Trim - Bank 1: -7.0 %
PID07 Long Term Trim - Bank 1: -3.9 %
PID08 Short Term Trim - Bank 2: -6.3 %
PID09 Long Term Trim - Bank 2: -3.9 %
PID0B Intake Manifold Absolute Pressure: 56 kPa abs
PID0C Engine RPM: 1559 /min
PID0D Vehicle speed: 33 km/h
PID0E Ignition timing advance for cyl #1: 38.0 Degrees
PID0F Intake air temperature: 36 °C
PID10 Mass Air Flow: 19.42 g/s
PID11 Throttle position sensor: 15.7 %
PID1F Time since engine start: 971 s


Based on the data from my tool and what (I think) I know about the car, I think the fuel trims 3 & 4 on my friend's tool were just max values of the tool since the car wasn't providing anything but I could easily be wrong. Looking at the data above, I can't see anything but please tell me if I'm wrong. I plan on looking everything over, checking the wires, running more scans and checking more real-time data now that it's the weekend and I have more time to devote to this.

Thanks again for all the help and sorry for the looong post.

 

Hi John - Thanks for the reply. I guess I was assuming wrong and reading the data incorrectly. Basically my thinking was that since the O2B1S2 was basically sitting at zero for long periods and then jumping between 0 & full, that it wasn't sensing well or being a lazy O2 sensor. I didn't think these behaviors could be the Cat. I did run some more logs except graphing directly in the program this time. While watching the waveforms it does seem that the O2B1S2 is lazy compared to the O2B2S2. Here are the screen captures I took:

The graph below was one blip of the throttle to about 3K RPMs and shows O2B1S2, O2B2S2, and Bank 1&2 fuel trims.

The graph below was two blips of the throttle to about 2K RPMs and shows O2B1S2, O2B2S2, and Bank 1&2 fuel trims.

The graph below was two blips of the throttle, the first to 1.5K RPMS (green dip) and the second to about 2K RPMs. The O2B1S2, O2B2S2, O2B1S1, and O2B2S1 channels are shown.

The graph below was two blips of the throttle to about 3K RPMs, showing O2B1S2, O2B2S2, O2B1S1, and O2B2S1.

I forgot about the WOT run but will try that today and see how it works based the information you provided. After I took the above graphs I was convinced that the B1S2 sensor was bad or lazy since it was basically only jumping from high to low with no small changes in between as the B2S2 sensor was showing. But from how I'm reading your post, I am now thinking that it's actually showing me that the Cat is bad.(?)

Will post the WOT run graph when I get it. Thanks again for all the help!

 

So, which one is which of the two downstream sensors? Is the red trace the B1S2 or is the green trace B1S2? The red trace looks good to me and the green trace looks to cycle a bit too much but it's still hard to tell with the limited info. I can't see what the horizontal scale is.

That WOT run data is important because the computer will go into open loop at WOT. When that happens the computer will go full rich on the fuel and the O2 sensors should indicate that. The Lambda upstream voltage will go low (they work opposite of normal O2's) and the downstream sensor voltages should go high and stay there during the entire time it's at WOT. If the downstream sensor drops lean during the WOT run then I might suspect a bad downstream O2.

The fuel trims look OK so my guess is a bad cat. Again, I wouldn't even consider replacing a cat and using the old sensors so I'd probably just replace both sensors first (I always replace in pairs) and if the problem still occurs then replace the cat.

Edit: The fuel trims look OK but are those short term or long term fuel trims? The long term fuel trims are more important and give a better indication of what the computer is doing. If those are long terms then fuel trims are fine. If those are short term fuel trims then we still need to know what the long term fuel trims are doing to know if they're OK or not.

 

All we're trying to do is determine whether an O2 sensor is lazy or the cat is not working. The other thing you can do to test O2 sensor responsiveness is to introduce a significant vacuum leak by pulling a vacuum hose and watch the O2 sensor data. That should run the O2 sensors lean until the computer corrects with fuel trims. Then plug the vacuum line back in and see if the sensors go rich again until the computer corrects with fuel trims. You can use propane to drive the O2 sensors rich, as well. Just pop the air filter box and introduce it into the air box without the filter. All the O2 sensors should go rich until the computer corrects with fuel trims. Then turn off the propane and the sensors should go lean until the computer corrects.

 

WOW you are an amazing source of information, thank you so very much!

I tried to do some more tests today but my wife said no way :no:, it's my day. Then during our drive to lunch the weirdest thing happened... I noticed the check engine light was no longer on. I asked her, when did it turn off? She said, I thought you cleared it again.
Now I'm a bit confused since yesterday afternoon when I checked I had a confirmed P0420 and a pending P2096, but I made it a point not to clear the codes. We did drive the car most of the day but at the end of the day the CEL was still on. My wife took a few trips this morning and then when I drove it was gone. :dunno:

 

Yeah, when the computer has a few drives where it does not see the problem it will turn off the light. You'll still have the codes in memory, though.

This is actually where Mode 6 data comes in. This is pretty advanced so I don't expect you to be able to do this but thought I'd explain it. On systems that are not constantly monitored and checked the computer will store the parameters it found during it's last test of that system. The parameters are stored in hexadecimal format in what they call Mode 6. It's often just a menu item for On board Diagnostic Results or some such thing. So you can go into the Mode 6 data in your OBDII scan tool (if it supports it) and view the actual results of the last test. This allows you to see how well the system passed. For example, if a passing result is somewhere below "10" and you are at a "9" then you know it's right on the edge and the light will likely come back. If you've done a repair and you view the Mode 6 data and it's now showing a 2 when prior to the fix it was showing a 15 then you've confirmed your fix without having to drive the vehicle through its entire drive cycle to set all the monitors.

Mode 6 is complicated because many manufacturers don't provide the parameter data to know what's good. Each system has a label like $01, $02, etc. and it can be hard to determine which system is $01 and $02, etc. Then once you determine which system is the right one then you still have to decypher the data. Some scan tools will give it to you but often you have to convert it out of hexadecimal format.

I was able to do this on a 2004 Toyota Sienna with a P0420. The AlldataDIY subscription I had did list the Mode 6 system numbers for the catalyst test. I was able to go in to the Mode 6 data and figure out that the number of up/down rich/lean cycles of the downstream O2 was being exceeded by quite a bit. It took me quite a while to decypher the data but I kept at it and figured it out. The computer uses the upstream and downstream O2's to determine the health of the cat. If the downstream cycles too much, and matches too closely to what the upstream is sensing (hard to see in live data because the upstreams are A/F ratio sensors,) then it will set code P0420. My plan was just as I suggested here. I figured it probably needed a new cat but decided to first replace the O2's and see what that did. After replacing the O2's I couldn't get the catalyst monitor to set but viewing Mode 6 data showed me that my number of cycles of the downstream sensor was WAY under the passing threshold and WAY under what it was prior to replacing the sensors. I confidently gave the vehicle back and told the owner they didn't need a new cat. They hailed me a hero and it's been a couple months now with no more check engine light on that vehicle.

 

Thanks again for the detailed info and sorry for the delayed response. I had an unexpected business trip and just returned. Unfortunately I wasn't the only thing to return.... the CEL is back. I did see Mode 6 on my scan tool so I'll see what I can find. I also plan to do the WOT run and see what that shows. Thanks again for all your help.

 

Hi All it's been a bit since my last post but I wanted to post my results just in case it can help anyone else. As the title says, I was getting P0420 & P2096 codes. So it was either my Cat which would be covered or my O2 sensor which isn't covered by warranty. Based on the info from John (Thank you very much!), I purchased the NTK 24093 sensor from Rockauto and just installed it.

I still don't know for sure (time will tell) but based on the graphs I ran and my gut feel, I am fairly sure the problem has been fixed. Before the replacement my B1S2 (Red line) seemed to "stick" either high or low and didn't adjust / jump as much as the B2S2 (Green Line), see below.

After the replacement the B1S2 seems to adjust / jump about the same as the B2S2 O2 sensor.

This tells me the problem is likely fixed and it was the O2 sensor this whole time. If by chance I am wrong, I will make sure to post again. Hope this helps anyone with the same issue. Thanks again for everyone who chimed in to help, especially John C.

 

Well, your P2096 code indicates that the downstream sensor was sticking low voltage, or lean. The downstream sensor should stay relatively steady in the 600-800mV range at idle. It shouldn't oscillate between high and low. It will go high and low when it sees rich and lean conditions such as acceleration or deceleration but generally should stay steady. The P2096 indicates that it was staying low for too long.

The way to know if you've fixed it is to look at Mode 6 data but that gets pretty complicated and, depending on the scan tool, means converting some hexidecimal numbers to something you can understand and anaylize.

 

I have the same problem with codes and i almost give up but i tried spraying a MAF CLEANER ON maf sensor and it never came back. Hope it help you guys