Smog Testing Readiness

Is there such a thing as data so borderline that the system won't pass or fail it and keeps letting it go to collect more data until it goes a hair one way or the other?

I've read that a bad downstream O2 sensor can cause it to not complete. The new one is Denso?

 

Gosh I hope that’s not the case. Yes. I replaced both sensors with genuine Denso parts.

 

So…..still haven’t completed the catalyst test. As you may remember, I replaced both O2 sensors a long time ago. I noticed recently this monitor on my OBD reader.
While I’m driving, O2 sensor 1 never shows any value but #2 constantly changes. Is that supposed to be that way? Wouldn’t I get a code if the sensor or the wiring harness was faulty?

 

were you able to find a solution to the catalyst monitor readiness being incomplete? got the same problem on my 03 prerunner 2.7, only about 250 miles into trying to get it ready with no luck yet. also replaced both 02 sensors a few months ago but then just had the head replaced earlier this month. first time on tacoma world in a few years so just now reading this thread, gonna try to get 20 minutes at 45 mph as soon as traffic on the 405 dies down

 

Yes! I did get it to complete. And you’re not gonna believe it, but I used this:

CRC Guaranteed to Pass Emissions system cleaner. I tried following all the Toyota guidelines to get it to pass for seven months. I put 800 miles on the truck, trying to pass. The truck was mostly parked except for me trying (because of the expired tags). Anyway, I followed the directions on the bottle and about 50-60 miles into that tank, I took it for a 30 mile freeway drive and it completed the catalyst test! Went immediately to the smog place and passed. Got my sticker in the mail. It didn’t last
long though, I got a P0420 again a few weeks ago. Cleared it and it hasn’t come back yet.

Some people in the Amazon reviews say they use it every six months and it keeps the cat cleaner. I might try that. But I’m sold on that stuff. Give it a go!