Smog failed due to "catalyst not ready"

Tiny
JIANWENT
  • MEMBER
  • 2004 TOYOTA SIENNA
  • 1.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 170,000 MILES
I fixed the "check engine light on" problems by replacing the new oxygen senor. After that, I have driven for more than 500 miles so far. However, it is still not ready for smog, because when the technician checked by OBDII, it indicated that "Catalyst not read". Does it mean I will fail the smog check? I was told that I need to drive more miles and fill the tank with high quality gasoline (91#). Is that true?

please advise.

appreciate your help.

Tenny
Tuesday, June 30th, 2020 AT 9:31 PM

27 Replies

Tiny
STEVE W.
  • MECHANIC
  • 13,572 POSTS
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.
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Tuesday, June 30th, 2020 AT 10:16 PM
Tiny
JIANWENT
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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".
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Tuesday, June 30th, 2020 AT 10:48 PM
Tiny
STEVE W.
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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.
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Wednesday, July 1st, 2020 AT 12:09 AM
Tiny
JIANWENT
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  • 14 POSTS
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?
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Wednesday, July 1st, 2020 AT 11:24 AM
Tiny
STEVE W.
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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.
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Wednesday, July 1st, 2020 AT 11:43 AM
Tiny
JIANWENT
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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.
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Wednesday, July 1st, 2020 AT 12:25 PM
Tiny
STEVE W.
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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.
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Wednesday, July 1st, 2020 AT 3:38 PM
Tiny
JIANWENT
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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?
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Friday, July 3rd, 2020 AT 5:55 PM
Tiny
STEVE W.
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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.
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Friday, July 3rd, 2020 AT 6:58 PM
Tiny
JIANWENT
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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.
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Sunday, July 5th, 2020 AT 9:23 PM
Tiny
STEVE W.
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Good luck. Let us know if it sets.
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Monday, July 6th, 2020 AT 11:48 AM
Tiny
JIANWENT
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  • 14 POSTS
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.

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Sunday, September 13th, 2020 AT 10:26 PM
Tiny
STEVE W.
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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.
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Monday, September 14th, 2020 AT 12:56 AM
Tiny
JIANWENT
  • MEMBER
  • 14 POSTS
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.
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Monday, September 14th, 2020 AT 10:59 AM
Tiny
STEVE W.
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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.
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Monday, September 14th, 2020 AT 2:23 PM
Tiny
JIANWENT
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Just want to make sure it has to drive between 55-60 for 10 minutes. Not 65 for 20 minutes?
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Monday, September 14th, 2020 AT 3:04 PM
Tiny
STEVE W.
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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.
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Monday, September 14th, 2020 AT 4:22 PM
Tiny
JIANWENT
  • MEMBER
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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?
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Monday, September 14th, 2020 AT 4:26 PM
Tiny
STEVE W.
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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.
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Monday, September 14th, 2020 AT 4:40 PM
Tiny
JIANWENT
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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?
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Tuesday, September 15th, 2020 AT 1:59 PM

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