I had the same issue with my 01, even after driving over 200 miles. I ended up replacing the post CAT O2 sensor with a Denso unit and cleared within 50 miles of driving it. Better the o2 sensor than the CAT. BTW I used the Torque app.

I can't remember what code it was, but the smog tech told me to just keep driving it "so the computer can get enough data". Mine took about 150 miles before it eventually reset and gave no codes. Wish I could get more technical...

I am in the same boat right now. my 3rd gen wont pass smog due to the readiness monitors incomplete. in need help DESPERATELY , i repaired o2 sensors , my exhaust leak, vacuum problems, cleaned throttle body and MAF and nothing seems to work!!! its very frustrating and ive been back n fourth to the smog center and the same thing keeps popping up that everything is ready EXCEPT FOR -- EVAP, O2, CAT, and 2 others aren't ready. ive driven the drive cycles multiple times now and nothing seems to be working. Ive heard to disconnect the battery to let the ECU but with my luck it wont do anything, im about ready to just pay $300 to 'pass' emissions. somebody please help SOS

You may have a cat going bad, or maybe you haven't driven it enough. First thing is, if you don't have a scan tool and know what you are looking for, you should have a pro try to solve it for you. Paying someone off won't solve the real problem, and you should solve it for sure. What do you mean when you say you repaired the 02 sensors?

My Son bought a 2001 2wd Limited with 220k. runs strong. passes smog but not the readiness test. we too have followed the test and my Torque tester says that it's still not ready for testing. My 1980 FJ40 was easier! i've been reading all the post and and have tried just about everything just shy of getting my money back from the previous owner of having HIM smog the dam thing. he put a new battery in just before he sold it to us.

Hey everyone,

I just recently purchased a 2000 Limited (California) from a friend and my first mistake was not getting it smogged right away. Did some electrical work on it (and in the process disconnected the battery), and when I went to smog it a few days later, it failed because the cat monitor was not ready. I drove it about 850 miles after that, went back to smog, and the cat monitor was still not ready.

After that, I found the Toyota Service Bulletin that described how to run the drive cycle for the cat monitor (linked here) and did it as best as I can 4 times. The cat monitor still refused to set.

So this morning I picked up a replacement O2 sensor and swapped it in. I haven't really driven the car since then but we'll see if that helps finally set the monitor. I'll drive it generally and also do a couple of drive cycles to see if that helps.

Barring that working, does anything else have suggestions for what I can do to get the monitor to set? If you need to know any additional info let me know too. Thanks!

You can drive that combo of mph/speed 100 times over, but if you have a bad gas cap the monitors still won't reset.

so... check/replace your gas cap. I don't mean "tighten the hell out of it" i mean, try a different gas cap if yours in 20 years old

My evap monitor is fine, it had no problems becoming ready. Would the gas cap still be preventing the cat monitor from being ready?

Hmm, well, I can't give definite yes or no.. But I mention the gas cap cuz my situation wasn't too different sounding last Fall.
I took a trip out of state and my battery died at the airport for that 5 days I was gone (door slightly ajar, overhead light on).
I jumped the car, drove home, thought nothing of it. Went to smog it the a day or so later because that was on my list of stuff to do that week. Failed the test.

Point is.. I was throwing cat and evap codes b/c of the battery dying and resetting my ECU. Was told "just drive a while and the codes will clear, come back and retest.."
Put 300 miles + on it over the next week or so, highway and city. Still couldn't clear it for smog-readiness. The guy even took my gas cap off, looked at it, cranked it wayyy down. then he showed me his book and said "take a picture of this drive pattern, do this exactly" and I did. several times. Still couldn't clear it.

but I had a spare gas cap and figured I should try swapping it out. Ran the drive pattern one more, cleared all my codes first-try.

So... long story aside.. I don't know if it's a "yes it totally works" but there are definitely times it seems to be something that simple.

Well I just did another drive cycle (and the first time I drove the car more than a couple miles today) and the cat monitor readied up! So looks like it was just a weird faulty O2 sensor. Thanks for the input though!

Nice! hey, any problem solved is a win. right? Glad you got it readied for smog!

I was also gonna point to the front O2 sensor.

I live in Texas, which allows 2 'unready' monitors on a pre-2000 vehicle and still pass, but I for the life of me could not net my new Walker Cat to be ready.

I eventually gave up because I got inspected fine, but then later replaced the front O2 sensor for an unrelated issue, and the CAT became ready the next day.

Hi, I am having similar issue with evap and cat not setting. It took 100 miles for the O sensor to come on. I never had a code pop up, so today I tried tripping a code by unplugging the evap sensor, and that didnt work, so I took off the gas cap too. Neither tripped a code. Reading this I would assume it would take 2 drives to make a code appear? Just trying to figure out if my computer is working properly, which I assume it is because the other monitors are ready?

So Far, I replaced the o2 sensors the the throttle position sensor and gas cap with no avail. Last time this happened I replaced the ground from the battery to the body of the car and that fixed it.

Yes, you need two drive cycles to set the permanent code for the evap or cat and light the CEL. If your code reader reads pending codes, you should be able to see if that is set after one drive cycle although the CEL will not light. Also, these monitors do not run continuously. They only run when the preconditions are satisfied - if the monitor did not run, it would not even set a pending code. Attached the TSB I referenced in my original post as I see my previous link is no longer working.

Attached Images

4Runner Drive Cycle.pdf (138.2 KB, 199 views)