smog failed due to "catalyst not ready"

What is the actual code that you have. There are many things that can prevent the catalyst monitor from running. Is the CEL out now? Did you use a scan tool to clear all of the codes? There can be codes that do not set the light on, but that can keep tests from running.

the CEL is off after the oxygen sensors have been replaced. the Scan tool only showed "Cat not ready". The mechanic just told me to keep driving more and use the best quality gasoline to fill up the tank. I asked him any other possible mechanic issues and he said "no"...

The Toyota drive cycle for that monitor to run calls for a warm engine, no codes of any type and then drive at a steady speed for 7-10 minutes at between 40 and 70 MPH. So say 10 minutes at 55 mph. Then check the monitor status. If needed drive the cycle again. If the monitor still does not set then you need to use a dealer level scan tool to check that there are no pending codes in any other system, as well as checking the O2 sensor signals to be sure they are correct. Better gas won't make a difference.

Thanks for your advice. I usually stop by the Smog Check station to have it checked on my way back home, with that being said, I have already driven the van on highway (65 MPH for about 10-15 minutes), but still, the OBDII monitor showed "CAT, not ready". I have been doing this in the past 1 month, after driving 100-150 miles, I will have it checked since my car registration is expiring soon. Unfortunately, up to this moment, the CAT still is not ready. is there a dealer level scan tool other than the one most Smog Check stations are using?

Most of those stations only look to see if the monitors have run, they don't really go any farther unless you pay them to repair the problem. A dealer level tool will scan all of the modules and look for anything that could cause it to not run a monitor. For instance say you have an EVAP code that is a 2 trip code (has to fail twice in a set time before it turns on the light) If the code sets once as pending but then clears itself for a while. which can happen if a purge solenoid or vent was to stick once in a while, you could have a pending code that many of the common scan tools wouldn't see, especially with this being a 2004 Toyota. The better scan tool would show that. Something like that can stop a monitor from running, but go undetected because it didn't trip the light on.

Initially, the CEL was on, so I paid the smog station to do a full diagnose and fixed the issues by replacing the new oxygen sensors. Then I was told I have to drive more miles, put high quality gasoline etc. in order for the Catalyst to be ready. However, the OBDII scanner still indicated "CAT not ready" and everything else all "PASS".Attached please see the SMOG report. The dealer would charge $200.00 for the diagnosis. Is it worthwhile? Please advice.

If you have driven the vehicle but it still has not set then there is something wrong. Either there is something blocking it from running or there is another fault that hasn't been detected yet. You don't have to use a dealer, just someone who has a full line scan tool that can check all the modules for faults. Another option would be to reset all of the monitors and drive it and see if it runs them all or sets the CEL on.

the mechanic who replaced the oxygen senors previously cleaned up the catalyst convert yesterday and I plan to drive more miles, then to check if the CAT is ready. Why "set the CEL on"? Is CEL supposed to be off?

It's possible that there is something that could trip the light on and clearing all the codes and monitors would make it happen. Hard to say for sure, but it wouldn't be the first time that repairing one problem that had turned on the CEL was hiding another issue that didn't show up until after the repair. For instance having a bad O2 sensor that was causing the engine to run rich and that damages the converter. You replace the Os and clear the codes and it all looks good, until the monitor can now run and it sets a P0420 code telling you that the converter is bad. Or another common one is having a misfire that triggers the light on, then the misfire dumps raw fuel into the exhaust and once repaired you get the same converter code because the fuel burnt it out. Not saying that is the case but normally the only problem monitor is the EVAP one that requires some odd conditions before it runs. The rest normally set pretty easy.

The Mechanic shop cleaned up the converter and asked me to drive more miles. There was no code indicating anything wrong. based on the initial check (see attached file), the EVAP is fine. I will drive more miles, then go to check again.

Good luck. Let us know if it sets.

Hi, it has been a while since I contacted with you last time. I have driven for more than 1,000 miles (most on highway) now and still the OBDII scanner indicated " CAT not ready". I was told to drive even more. One friend suggested me to try this product:
https://www.autozone.com/fuel-and-engine-cleaners-additives/fuel-additive-and-cleaner/cataclean-fuel-cleaner-16-7oz/227800_0_0?spps.s=4091&cmpid=LIA:US:EN:AD:NL:1000000:PER:71700000060528029&gclid=Cj0KCQjwwOz6BRCgARIsAKEG4FVPnFE-X-RVlOG3de8YsadWFwWVYvAzVsY3R_aEk6J_PymY_YYJNBYaAifZEALw_wcB&gclsrc=aw.ds
do you think it will help?

Appreciate your advice.

There has to be something blocking that monitor from running. I doubt it is a bad converter as that would set a different code. There are a couple items that are monitored before the test will run. The engine coolant temperature is the primary one. Run the engine for a while and use a scan tool to see if the coolant temperature is coming up properly. If the system thinks it's running cold the test won't run. After that the below text is the factory drive cycle. Note that you may need to drive this a few times and that just driving around will not set it. Also the driving at the steady speed means staying at 55 or so for the entire 10 minutes, if you slow below 40 or drive over 70 in the run it stops the test until the next engine start cycle.

Do not turn off the ignition switch during the test procedure.
Allow the vehicle to run at idle until warmed up.
Drive at a steady speed between 40 and 70 MPH for 10 minutes. It’s a good idea to stay in the middle of this range, so 55 MPH is optimal.

I usually drive the vehicle to work 3 days per week now (one way from home to company is about 13 miles, out of which 10 miles are highway with 65 MPH and the rest of are local with 20-40 MPH). It will take about 20-25 minutes one way. I stopped by the smog station on my way back home to have it checked in the past... Do you think what shall I do differently based on our experience?

I will bring it to the shop to check the engine coolant temperature next time.

Appreciate your advice very much.

Once you are sure it's warming up properly the try to drive at least 10 minutes, at 55-60. 10 miles at 65 is under the time threshold of the test. Take it for a longer run, say 20 miles one way at 55-60 then shut it off, restart it and drive back and see if it runs. Toyota's can be a bear to get this to run, so I try to do about double what the drive cycle is and see if it will run.

Just want to make sure it has to drive between 55-60 for 10 minutes. not 65 for 20 minutes??

55-60 for at least 10 minutes at least, I usually go longer on them because they can be a bother to get them to set. So 15-20 minutes would be better. Then shut off the engine, restart and drive back the same way. Then see if it set.

it is easy for me to drive 65 for 15-20 minutes, because I usually commute on highway for that speed. Is it okay instead of 55-60? When you said "Then shut off the engine, restart and drive back the same way.", do you mean immediately or I can wait until I finish work, then go home to drive the same manner?

The system will stop the test at 70, so how accurate is your speedometer? That is why I say 55-60. Say your tires are slightly off size and the speedometer is off by 3 mph. You run 65 and are really going 68. That is a bit close if you go up or down a slope. If you can run 15-20 nonstop, then work and come out, you will need to let the car warm up before you head back as it needs to be warm prior to the test starting. Say you get ready to head to work, jump in the car, start it and head out. You drive 15 minutes to work at 65 mph. It may take more than 5 minutes for the engine and converter to even warm up. So now you have barely 10 minutes for the test to run. That is why I suggest the run without other stops. The car will warm up on the first run, then you know it is warm when you come back.

I don't quite understand what you mean by "The system will stop the test at 70". So I drive at 70, the "CAT" won't be ready?

Correct. The system runs the test for the converters only at speeds between 40 and 70 mph. Slower or faster and it will not run the test because the exhaust flow is outside the "normal" speed zone the vehicle operates in. IE not enough flow at 40 and excessive flow at 70. So Toyota specifies the speed and time required and suggests staying more toward the center of the speed and a bit over the time to enable the test to run.
The idea is that gives the converter enough time to operate for the system test to say Yes it's ok or No it isn't. Toyota isn't the only one with odd rules for monitor tests, but it's one of the top 5.

got it! Sure I can drive around 60 on highway for 15-20 minutes, then once I exit from the highway, I can only drive around 30-35 before going to the smog check station, is it okay?

That should be fine. Start it and let it run a bit before you start out, that will give it a chance to warm up. Sorry if it sounds like it's a bother, but Toyota for some reason made this a bad test to run. Other cars will run in like 5 minutes with random driving.Not Toyota.

how many days shall I do the following cycle? For example, in the morning, before I go to work, I start the car and let it run for a few minutes, then I will drive 2-3 minutes with 25-30 MPH on the local way before going on the highway. I can drive around 50-60 MPH for 10-15 minutes, then exit the highway, drive 2-3 minutes local way arriving the company. In the afternoon I will do the similar above pattern... I usually go to work 3-4 days every week currently. Is it possible that I will miss the points when the CAT is ready, then after certain points, the CAT become not ready again?

I would say that 2 days or 4 trips should make the monitor set if it is going to. You don't need to worry about missing it, once set it will stay that way until it fails the test at a later time or something resets the ECU. In theory it should run on the first trip, but It can take more.

Does it necessary to be consecutive 2 days? Is 50-60 MPH on highway for 10-15 minutes okay?

Nope, you just want to do it more than once. 55-60 for 15 minutes would be a minimum to be sure the test requirements are met. Longer is better in this case.