The voltage numbers you mentioned in the opening is what I've always used as "normal".
Not sure what the issues your chasing is? Would you know about the readiness tests without regular scanning?
Throwing a code, not passing an inspection, not running right?

 

It shows up as not ready when I do a smog scan with the OBD2 device. Yet there are no codes, no check engine light, no sputtering issues or any of that. I can't find anything wrong on the scan. Just "test not complete" shown next to each untested thing. I've tried all of the drive cycles, as well. At my wits' end. Got a 30-day extension on the tag because it will certainly fail emissions with the untested items. We went through this exact same thing last year with emissions. Last year a Senior Toyota Tech at a dealership vaguely mentioned something about changing a couple of pins, but that's not on the paperwork at all. Instead, he noted something vague on the paperwork that said he drove it at like 55mph with two 30-second stops. That obviously isn't the issue...we've done that plenty of times.

 

I modified your thread Title so maybe we can get more people incolved. I can change it back if you want.
What brand and source of O2 sensors?
So you were scanning it to prep for emissions or did it actually fail so the extension was granted?
I may have missed it but have you tried a different scanner.

 

It failed emissions at the dealership. The new techs were clueless. The one that fixed it last year is no longer there. The customer rep said it "would be a very expensive fix" and started talking about replacing the whole ECU/computer and that sort of thing. The emissions testing also reflects the same untested items and that it failed readiness for the O2 sensor/catalyst. They also wanted $158 just to have a tech hook up a similar scanner and drive it. Any mention of a customer scanner and they'll automatically assume it's no good at all, even though I use BlueDriver that is among the top 5 scanners and shows more than their top-of-the-line hardware scanners show. They'll try to blame the bluetooth scanner for it and did last year. Whether I told them about it or not this year, their viewpoint didn't change on what to recommend. So I didn't tell them this year and it's the same. They couldn't blame the bluetooth device and now blame the car's ECU computer as a whole and think it is 'bad'. Never heard of such a thing.

 

When you erase the computer with a code scanner or by disconnecting the battery, your car will not be ready for smog testing. It just won't be. It needs to be driven about 50 miles at freeway speed to develop readiness. Do not think you can erase the computer and that fixes real problems- if there are any problems. You create the "not ready". Wait until the scanner says the car is ready before trying to pass a smog test. If the check engine light came on, test the parts and systems related to the trouble code. Parts that test bad should be replaced. Parts that test good should not be wasted.

 

No parts have tested bad. Drive cycles are not working properly. Car has been 100+ miles since reset. Highway speeds, city, stop and go, warmed up, etc. Everything tested already but the downstream O2 sensor and catalyst which have not tested. This is a 2+ year problem.

 

What brand O2 sensors.
So drives fine but will fail if scanned or is the CEL ? Does your scanner provide live data like fuel trims?
Have you ever shot the cat. with a temp gun to see after a drive if the temps are even, i.e, no cool or cold spots?

 

What brand O2 sensors.
So drives fine but will fail if scanned or is the CEL ? Does your scanner provide live data like fuel trims?
Have you ever shot the cat. with a temp gun to see after a drive if the temps are even, i.e, no cool or cold spots?

Yep and everything looks fine on the Live data. Haven't tested the cat with a temp gun.

Does anyone know if the Mass Air Flow sensor above the air filter under the hood has any effect on the downstream O2 sensor testing properly? This is one of the things that hasn't been replaced.

 

I don’t do drive cycles. Reason being, just driving it does the same. Forcing the system to show readiness is hard as is.

Personally, I don’t wait until the last minute to check monitor readiness. Evap is one that takes the longest to be ready. Cat and O2 takes time also, but not as long. Just drive and if not driven daily, take it for a short trip.

This last emission test I did, took almost an entire month for the o2 readiness.

 

Which monitors are not setting?
Any codes stored in the ecu?

 

Downstream O2 monitor is testing 2 or 3 of the 5 total tests for it and intermittently varying in how many are tested.
Catalyst has simply not tested yet and is likely waiting on the downstream O2 sensor.

The car has only one upstream O2 sensor (engine - both tests successfully completed) and one downstream (near/on catalyst) and the downstream simply varies frequently in how many tests are complete. It never goes all the way. At the most, it stops at 3/5 total tests and then goes back to 1/5 or 2/5 tested.

I have particularly noted that it is getting the right voltage on the downstream sensor and also the Heater Monitor is testing, so no wiring/voltage issues on part of it are of concern at this point. No codes in the ECU. Completely clean when I scan all modules. When I run the smog test, of course, it just says that the downstream O2 sensor and catalyst haven't tested yet. Last year we had this happen, too. A senior Toyota Tech did something to make it pass emissions and now he retired and we don't know what was done. They have no clue and wanted to change out the whole ECU, lots of other parts in a trial-and-error. New plugs 3 months ago, new air filter, oil is clean and changed regularly, no misfires. Over the past 2 years, 3 new oxygen sensors (Denso - Toyota) have been put on. I'm at my wits' end. With the exception of the evap test that requires being off overnight for like 8 hours and 40F or so temps, everything else tests within a single day of driving to/from work. We drove it over 600 miles last year with all sorts of city and highway driving and it did this same thing with the downstream O2 not testing and the catalyst not testing. Tried hard and soft accelerations, various speeds for x and xx minutes, etc.

Looks like everything has voltage and is working properly in Live mode for the components in question.

 

3 brand new o2 sensors in the past few years with a short life indicates a problem. When you say that there’s no wiring issues, does this mean you physically checked the o2 sensor? Or is this just based on the blue driver?

The o2 sensors typically are to be replaced in pairs. With no short term fuel trim data suggests that the downstream o2 is an issue. Mine took like a month for the o2 sensors to set the monitors.

What state are you in?

 

Georgia. I didn't change the upper O2 because it tests both of its own tests immediately after reset.

As for the fuel trim, both the short and long are adjusting frequently and the open loop and closed loop are visible for the fuel trim mixtures depending on accelerating and decelerating. The Mass Air Flow sensor that I was talking about before also seems to be working. This is a really interesting problem for sure.

 

You can test your downstream o2 sensor off the vehicle. You will need a few items.

multimeter
butane torch
alligator clips for the sensor pins/terminals
temp probe (if multimeter doesnt

Locate/identify the signal and ground.
Connect leads to the o2 sensor terminals
Apply heat to tip and get it to ~600 degrees F.

Remove the heat source and watch how fast or slow the sensor reacts. A good sensor will fall fast.

For your cat, tap on the housing or shake it to listen for loose bits. It is very possible it has fallen apart due to age.

 

You can test your downstream o2 sensor off the vehicle. You will need a few items.

multimeter
butane torch
alligator clips for the sensor pins/terminals
temp probe (if multimeter doesnt

Locate/identify the signal and ground.
Connect leads to the o2 sensor terminals
Apply heat to tip and get it to ~600 degrees F.

Remove the heat source and watch how fast or slow the sensor reacts. A good sensor will fall fast.

For your cat, tap on the housing or shake it to listen for loose bits. It is very possible it has fallen apart due to age.

Is it common for Toyota cats to fall apart after just 10 years? The previous car was a 1992 Ford Escort and that thing was sold to my uncle after like 20 years and it still passed emissions fine. Never had the cat replaced or serviced at all.

 

Cats fail at different times. Not all are going to fail at the same time. It could have had less of material than another. When cats don’t reach the temperatures, does cause it to fail earlier than designed. Exhaust leaks will cause issues for the cat efficiency. Not allowing for the cat to warm up does impact it also. O2 sensor failures also impacts the cat.