Dreaded Catalyst Monitor 02 Tacoma

I have an 02 Tacoma 3.4 with all codes passed except the catalyst Monitor. I've done the drive cycle multiple times with an obd2 plugged in to check and make sure the temperatures were at the levels they needed to be at (or. Greater than 80c coolant and 10c outside temp/intake temp) yet it would not pass . Put about 400 miles on it still nothing.

Changed rear o2 sensor reset codes and all passed except cat monitor. Drove another 400-500 miles.

Now I replaced both cats because I was tired of it. And one of the cats had the inside comb pretty much falling apart when I took it off. Hoping that was the issue I drove another 225miles and it still hasn't passed but I havnt done the actually drive cycle since I changed the cats. I will attempt this next. But I'm running out of things to fix. No codes have shown this whole time just a not passed/not ready line on the catalyst Monitor. Any suggestions? The drive cycle I'm using is the #4. Because at the top of the EG003-02 it says it's for a tacoma with a 3.4.
If you have anything to share Id love to get some help. I'm in california so they don't let that monitor go.

 

Welcome to TacomaWorld
I've never seen this before.
Any signs of wiring harness being chewed by mice?

 

No signs of it all the wiring looks good. I mean if the o2 sensor is passing I can't figure out why the cat won't. But it does say the cat is AF type not O2 type so my research tells me that the front o2 sensor(actually an air fuel sensor) is what determines the air fuel ratio so If that isn't good then maybe it's the front o2 sensor I got to change but it looks brand new so I figured it was already changed.

 

Tacos are sensitive to aftermarket sensors and many buy counterfeit sensors from eBay or from OTHER providers through Amazon.
DENSO A/F and O2 sensors have solved many baffling issues.

https://densoautoparts.com/find-my-part.aspx

 

But if the sensor wasn't working shouldn't the o2 sensor monitor be failing as well?

 

all of the suggested drive cycle parameters I have read start with letting the truck idle until it is warmed up ~10 minutes. You might not even have started the monitors.

As I was driving around the RSX that I am currently working on, doing the exact same thing... Cat monitor not running... I got to thinking about just how much time is wasted when you dont even know if the PCM is in "test mode". Other manufacturers give you a hint if the monitors have completed if you watch the CEL during the key on engine off phase by either flashing the CEL after the bulb check portion of the start cycle being completed. Sometimes I have been more sucessful clearing all the monitors by resetting the PCM and then taking the vehicle for an extended drive in the late evening when there is no one on the road so that I can drive @45 mph without causing a traffic jam.

 

Damn, you replaced both your cats and you didn't even have a P0420 code?

 

Nope no code and everytime I let the truck warm up for about 15mins to make sure it was at temp and if the pcm wasn't ready then none of the other codes would have processed either like the o2 and evap

 

Hopefully this weekend I'll have time to drive to the foothills ie. the only long road without stops on it to be able to drive slow haha. Is there a way to know if the pcm is processing Glen?

 

Sometime it's better to start over and fresh again. I recommend erasing any and all memory even though there's no pending code. Make sure your tank is always between 3/4 and 1/4.

I thought someone from socal was able to smog their tacoma with 1 pending monitor?

 

You can smog it with one pending code but that one pending code is only allowed to be the evap for 2002->newer.

 

Have you followed the drive cycle to the letter? some can be difficult to complete if you don't follow it exactly.

 

Not really. The parameters for a 02 sensor to cause a failure code are pretty extreme. It would have to be either gone, wrong part, or really really messed up to not pass a check.

 

excellant information. I am going to print that out. Check pending codes. From Dm93's upload.

This I did not know.

NOTE:

The readiness status may not switch to “complete” after the first drive pattern trip if a Pending Code has been set (first trip for a two–trip DTC).S Pending Codes are available from the DTC Info Menu in Enhanced OBDII.S Pending Codes indicate a POTENTIAL problem was detected. A second trip is needed to confirm the DTC prior to diagnosis.S Once a second trip is completed, a current DTC will be stored.


and another question I have been searching for an answer has been answered.

NOTE:

S These drive patterns represent the fastest method to satisfy all necessary conditions which allow the specific Readiness Monitor to complete.

S In the event that the drive pattern must be interrupted (possibly due to traffic conditions or other factors) the drive pattern can be resumed and, in most cases, the Readiness Monitor will still set to “complete.”

S To ensure rapid completion of Readiness Monitors, avoid sudden changes in vehicle load and speed (driving up and down hills and/or sudden acceleration).

 

I've done the drive cycle pretty close to perfect just maybe a stop sign because Its not really possible to drive for 20mins at that low of a speed without traffic changing your speed. But as stated above it shouldn't matter if I stop for one stop sign because it should just resume when I reached speed again.

 

Or do you think it's that picky on the computer?

 

@Jakethewhite hey curious if you found a solution the your cat monitor issue. I'm in the same boat right now. Thanks

 

@Jakethewhite + @jjnicolas any updates?

I am having the exact same issue with my ‘02 Tacoma xcab. Everything is OK but the Cat Monitor. Drove it 2,000 miles before smogging it in CA to get registered and recently discovered this forum and the drive cycles because of the failed smog test.

Have done cat mon drive cycle #4 twice and cat mon on OBD2 is still incomplete.

 

It's probably best to start fresh. Clear/reset the ecu and start all the drive cycle over.

My buddy couldn't get his cat monitor to set after 2 week and ~1k miles. Told him to reset and start fresh. He did, next day after 1 hour of driving, all monitor is good.

 

@BeardedTrucker5000 are you getting a p420 code? I changed out my cat and did the drive cycle. Cleared with one drive cycle