Honda CRV catalyst monitor wont run-interesting twist

Phil Technician Massachusetts Posted   Latest  
Case Study
Emissions
2011 Honda CR-V EX 2.4L (K24Z6) 5-spd (BZHA)
P0420 — Catalyst System Efficiency Below Threshold Bank 1
Unable To Pass Ma Inspection

Good morning all. Just wanted to put together a post about an interesting Vehicle I had this past week. Backstory on the vehicle is that it was purchased in April of 2020, not inspected until June and has never passed inspection despite several attempts, the vehicle is always NR. Inspection history shows the PCM being reset several times by looking at warmups since codes cleared and distance since codes cleared which is stored in OBDII generic data. There is also a permanent P0420 stored. Generally speaking we don't have problems with Hondas and readiness here in MA. Knowing that it had a catalyst code in the past and the inspection history showing multiple PCM resets I am suspicious. A discussion on the phone with the boyfriend of the owner doesn't reveal much information. I visited the shop where the vehicle was brought to and a visual inspection was performed.

Initial scan reveals catalyst and evap monitors NR. OBDII generic shows 11 warmups and 211 miles since codes were cleared. The only code is a permanent P0420. A visual examination reveals a relatively new battery and a newer looking aftermarket catifold assembly. And of course I wasn't shocked to find a spacer on the rear o2 sensor. What I also found however was a spacer on the AF ratio sensor. I have only seen this level of stupidity 2 other times. Once was on a late 90s Mazda MPV that had spacers on all 4 o2s in order to try to pass inspection. The other happened to be on a 2013 Honda Accord that I also saw last week. I'll post about that one later. It's bad enough trying to cheat the emissions test, but a spacer on the AF ratio sensor is likely to cause drivability problems at the least and who knows what at the worst. Both spacers are pretty crusty and old, they have been there for quite awhile.

I had some time for some quick not terribly scientific testing so I grabbed some graphed data of fuel trims and o2 PIDS with the vehicle sitting in the bay. First image is with both spacers in place. Second image is with the spacer removed from the AF ratio sensor only. It is interesting to note that the lambda reading and AF ratio MA readings changed when the vehicle is returned to idle after revving the engine to 2000 RPMs or so. Again not a very scientific test but there is a difference. You can also see a change in the activity of the rear o2 sensor. I don't put a lot of faith in looking at rear o2 activity to decide if a catalyst is bad but it can kind of give you an idea if the catalyst is likely to fail or not. Third image is with the AF ratio and the rear o2 spacer removed. Not really any difference between image 2 and image 3.

The mode06 data shows no result for the catalyst test since it hasn't completed yet. The vehicle was driven and the catalyst monitor completed within 6 minutes and per the mode06 data passed with flying colors. Sadly I forgot to save the graphed data of the drive cycle being performed. You can see the monitor ran when cycling between 30 and 40 MPH. I expected it to run during the first 55 MPH cruise and when it didn't I advised to do some cycling from 30-40. I'm assuming one or two performance tests on the AF or o2 had to run before the catalyst monitor would run because the PCM was probably a bit confused due to the spacers being removed. You can see the Mode06 data did update for both the AF ratio and the o2 sensor on the short road test.

Later on when talking to the boyfriend more information came out. After the initial inspection, the battery died. After the battery was replaced the MIL came on. That is when the catifold was replaced he believes. The shop that replaced the catifold told the motorist that the “sensors were out” but didn't explain further and she didn't pursue it. The kicker is that they reinstalled the AF ratio sensor with the spacer on it back into the top of the catifold! I'm betting that if they had removed the spacer that the vehicle would likely have run the catalyst monitor and passed. I see lots of spacers being installed, quite often along with the catalyst in an effort to get the aftermarket catalyst to not turn on the MIL. The older the vehicle the more likely the spacer trick can work, the newer vehicles are much better about performing o2 and AF sensor diagnostics and will either code for low activity or just won't run monitors.

I hope no one on this network is installing these spacers, if you are please stop. Install a quality part, fix the vehicle correctly, and make a proper profit. If you know someone who is installing them, please educate them and elevate the industry. This kind of baloney makes all of us look bad.

BTW, in MA we can pass inspection with any one monitor NR on the initial inspection. If the vehicle fails inspection with a catalyst DTC then upon reinspection the catalyst monitor must be ready for the vehicle to pass.

Thoughts? Comments? Questions?

+10
Helpful
Interesting
Thanks
Stuart Mobile Technician
Illinois
Stuart
   

Thanks for sharing​.​ Here in Illinois we have many shops that try to cheat the emmisions tests because the customers refuse to pay for the proper fix​.​ Some shops don't even have the proper tooling to even do a proper diagnosis. I am different, I will not take any work unless the customer is willing to pay for a proper diagnosis.

0
Ð Awarded
Randy Diagnostician
Colorado
Randy
 

Thanks for posting! I had one last year with an aftermarket Federal catalytic converter that had the rear O2 extender built in. It was failing IM240 but no DTCs. Today I had a 2012 Equinox, incomplete tests. I will post the PDF for discussion. Pretty simple to see what was going on with it but I ran an IM240 with extended idle afterwards to complete cat. I figured you would enjoy looking at the…

+2
Ð Awarded
Stuart Mobile Technician
Illinois
Stuart
   

They still do the IM-240 test in Colorado? Here in Illinois they did away with it in 2007 and only do the OBDII tests and any vehicles pre 96 don't get tested​.​ Their imfamous wisdom is that the pre 96 vehicles on the roads are dwindling so why put the effort and funding for testing them​.​ So their rationale means the biggest polluters won't get tested​.​ This is the type of thinking that is…

0
Ð Awarded
Phil Technician
Massachusetts
Phil
 

We only test OBDII vehicles here in MA as well. Although we do it a bit differently. We do it on a rolling 15 year window. Currently we only test 2007 and up vehicles. Next year it will be 2008 and up. The last time that I saw the numbers, the number of vehicles that do not get tested is less than 10%. The winters here just eat cars up, and it also seems that the later the vehicle, the worse it…

0
Ð Awarded
Stuart Mobile Technician
Illinois
Stuart
   

Ok then you do the IM-240 testing as part of the diagnosis process​.​ That is great if you have a dyno.I have used my gas analyzer many times to help diagnose OBDII problems​.​ But not for IM-240 type of test.

0
Ð Awarded
Phil Technician
Massachusetts
Phil
 

Ahh yes, 0 warmups and 0 miles since codes cleared upon arrival, but I swear, no one is clearing codes! Hear it all the time. Funny how the tune changes when you clue them in that there is a lot of data that mechanics have access to that tells a different story. The catalyst monitor passed, although just barely. I don't see these often with the mode06 intact and catalyst ready. I'm assuming as…

0
Ð Awarded
Randy Diagnostician
Colorado
Randy
 

Based on the data, it wasn't a ECM power loss either. I'm not sure what you mean by “I don't see these often with the mode06 intact and catalyst ready”? The whole topic of “if mode $06 is close to cut point, it is near failing” is a myth. At least for most mode $06 results and the GM cat results are one of those. IM240 Results. All in grams per mile (gpm) HC: 0.2472 CO: 2.228 CO2: 489.5778…

0
Ð Awarded
Phil Technician
Massachusetts
Phil
 

I did notice the time stamp of the tests but forgot to mention it. Personally I like to wait a bit longer to confirm a KAM issue. I remember a Suzuki that took over 10 minutes I believe before it would lose it's memory due to a KAM issue. Most cars are pretty much shut the key off and it will dump the memory if it has a KAM problem, but after that Suzuki I like to test them longer. You never…

0
Ð Awarded
Randy Diagnostician
Colorado
Randy
 

No, the data is the mode $09, that's what tells me it wasn't a power loss. I knew after the first scan what was going on. I did do all the other key cycle stuff just to prove it out but I understand your caution statement about leaving it off longer. I would do that if the $09 reset. I get certain GM model years for O2 and cat incompletes. There is a whole host of issues that prevent the cat…

0
Ð Awarded
Tony Owner/Technician
Missouri
Tony
   

Now mode $06, that probably should be another thread but I had some conversations with various OBD engineers that were pushing to remove $06 from generic data. One of the issues they kept bringing up was technicians were replacing parts based on $06 results that were “close to failing”. They stressed over and over that it doesn't work that way, it's not a linear result. Agreed, however my…

0
Ð Awarded
Geoff Diagnostician
Hawaii
Geoff
 

Thanks for the pictures. I had only read about the spacers, never seen them. No emissions testing here, so no need for anyone to try and cheat. (They just plain don't fix it.)

0
Ð Awarded
Phil Technician
Massachusetts
Phil
 

I've seen your stories many times both here and at the other site. I don't know how you handle it sometimes. We are “fixers” by nature. To not be allowed to fix things at least on occasion would drive my nuts.

0
Ð Awarded
Geoff Diagnostician
Hawaii
Geoff
 

Internet therapy! LOL We do fix cars that won't run, so there is /some/ satisfaction.

0
Ð Awarded