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Monitor not ready - catalyst evap system o2 sensor

Discussion in 'Prius c Technical Discussion' started by be_savvy, Mar 8, 2023.

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  1. be_savvy

    be_savvy New Member

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    Hi - first time poster here. I just tried to do my inspection on my 2014 Prius C and I got the 'monitor not ready' code.

    Some background information...
    A few weeks ago, my car wouldn't start and I was getting a bunch of weird lights on the dash and funny noises. Some light research suggested that the 12v battery might be the culprit. I used a friend's car to jump start and it started right up with no issue, so I went ahead and replaced the battery. I tried the inspection at a self-service kiosk that just has an OBDII cable. It failed.

    I did some reading and people mentioned the drive cycle and gave certain steps to take, which mostly involve driving at speed. I live in a city and have to drive a good 15 minutes at city speed to get to a highway. I don't really understand the issue. If I get the drive cycle to get the monitor ready once, am I good from then on? Does this have to do with the battery? Could it just be that the O2 sensor is bad?

    I tried the self service kiosk for a second time, where I sat with the car running at load for 5 minutes before running the inspection test again and it failed for a second time.

    I really have no idea what to try now.

    Thanks for any information.
     
    #1 be_savvy, Mar 8, 2023
  2. ChapmanF

    ChapmanF Senior Member

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    If you have access to a laptop with Techstream (or if you have access to a person who has access to a laptop with Techstream), it could be useful to pull up the Monitors display and see which one(s) it's calling incomplete.

    There are several monitors for different issues, and they take different kinds of driving patterns to complete. Usually if you just do enough random driving for long enough, they all will complete, but that's not as helpful if you've got one or two not completed yet and you're in a hurry for an inspection.

    You can concentrate on driving the confirmation patterns for just what's not yet complete, if you know that. The confirmation patterns are all in the repair manual:

    Toyota Service Information and Where To Find It | PriusChat

    Also be sure to note whether there are any trouble codes being shown. You didn't mention any. But certain trouble codes will prevent certain monitors from running, so those would have to be fixed first.

    Also, don't just go doing any code clears (or unhooking the battery, same thing), because that sends all the monitors back to incomplete and then you have to wait for every last one to complete again, not the best move if you're facing an inspection deadline.

    When you are looking in Techstream and see what monitor(s) it's calling incomplete, and then you want to find the right confirmation driving pattern(s) in the repair manual, there is one step where you have to match things up on your own:

    Techstream will show monitors by the description of what they monitor. For example, "catalyst efficiency" is the name of one of the monitors.

    The repair manual shows confirmation driving patterns under different trouble codes. For example, P0420 is a trouble code, and the section for that code has a confirmation driving pattern.

    It also happens that P0420 is the code you get if the catalyst efficiency monitor completes with a not-passing result. So that's where you find the right confirmation pattern for that monitor, and it's easy if the monitor completes and doesn't pass, because then you have a P0420 code that sends you straight to the right place in the manual.

    But when you just have a monitor that hasn't completed at all, hasn't passed or failed, then you don't have that trouble code to send you straight to the right place. Then you kind of have to peruse the codes in the manual until you know which code is the one you would get if that monitor failed, and that's the one that tells you the right confirmation pattern to drive.

    Edit: I just looked in your title, and it looks to me like three different monitors are identified there: "catalyst", "evap system", and "O₂ sensor" are separate monitors.

    As in my example above, the confirmation driving pattern for the "catalyst" monitor should be the one you find in the manual under the P0420 code.

    The "confirmation driving pattern" for the evap system monitor is more like to park the car and leave it alone for several hours, because that monitor is the one that runs about five hours after parking, and makes people wonder why the car is humming when it's turned off. It can also be run on command from Techstream and takes about 18 minutes. That should be described in the manual under P0455 / P0456.

    I'm not immediately sure which code(s) give the right confirmation pattern for the O₂ sensor monitor. As I said, one has to sort of brute-force search the manual to match those up.
     
    #2 ChapmanF, Mar 8, 2023
    Last edited: Mar 8, 2023
  3. be_savvy

    be_savvy New Member

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    Wow - so complicated! I'll have to check the paper with what the actual fail message was. I got the impression that it was all related to the O2 sensor and that it is a part of the named system. It definitely didn't say that the monitor failed - just that it wasn't ready. I'll check that link you sent. Thank you!
     
    #3 be_savvy, Mar 8, 2023
  4. be_savvy

    be_savvy New Member

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    @ChapmanF - thanks for your input on this. I do not have friends with this tool. I'm not a car guy - just a DIY guy.

    Anyway, after reading your post and doing further research, I finally understood what this all means - or at least I understand it enough. I reread the printout from the self-service inspection kiosk and saw that in fact, there were no error codes. And there were four separate monitors that were not ready. This probably should have been obvious, but I hadn't gotten there yet. So last night, I drove around the beltway - 15 minutes to get to the entrance at city speeds, an hour around the beltway and then 15 minutes back home. Took it this morning to the same self-service inspection kiosk and it passed. WOOHOO! Thought I was going to have to spend a bunch of money on this one.

    Thanks again! Now I have to get this thing cleaned up to sell it.
     
    #4 be_savvy, Mar 15, 2023
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