When Your DTC "Readiness" Monitor Status is ABNORMAL

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by NoThrowningRocks, Mar 1, 2022.

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  1. NoThrowningRocks

    NoThrowningRocks Junior Member

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    Having problems getting rid of P0420 (just had catalytic converter replaced; getting new O2 sensor installed tomorrow) and P0A93 codes to pass emissions. While going through the the AF/O2 Sensor testing process from TIS, I came across this "All Readiness" section of Utilities. Oddly, the P0A93 status was "normal," but not for P0420.

    I read @ChapmanF comment here (back in March 2008), but I am still a little confused. Since the P0420 DTC code is showing, I partially understand why the "Monitor related to the input DTC would be ABNORMAL" along with a Check result of NG (no good?). However, the P0A93 DTC is showing and its monitor is NORMAL with an "Okay" check result.

    Is this anything to be concerned about and does it tell me anything about the status of the two codes?
    Thanks!

    P0420 Monitor related to DTC is ABNORMAL.jpg
     
    #1 NoThrowningRocks, Mar 1, 2022
  2. ChapmanF

    ChapmanF Senior Member

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    What is showing under Trouble Codes for your P0A93? Is it shown as a current, pending, historical, or permanent code?
     
    #2 ChapmanF, Mar 2, 2022
  3. NoThrowningRocks

    NoThrowningRocks Junior Member

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    P0A93 is current and historical at "normal" status and P0420 is hit all three boxes with an "ABNORMAL" reading.
    Health Check - DTCs as of 2022-03-01_12-13-17.jpg
    P0A93 Monitor Related to DTC is NORMAL.jpg
    P0420 Monitor related to DTC is ABNORMAL.jpg

    Thanks!
     
    #3 NoThrowningRocks, Mar 2, 2022
  4. ChapmanF

    ChapmanF Senior Member

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    You have run the All Readiness Utility from the Engine and ECT tab. P0420 is an Engine and ECT code, but P0A93 is not. That's a Hybrid Control code. So the engine and ECT readiness utility is just giving you default information for a P0A93 code it knows nothing about.

    For the P0A93 code, you will see more/better information on the Hybrid Control screen. Also, you have a freeze frame for that code, so it would be worth finding out what that says—in particular, the 3-digit INF code.

    What the P0A93 code means is that the power electronics aren't getting cooled effectively. The INF code will tell you whether the ECU thinks that is more likely the fault of the electric pump or the cooling fans. The freeze frame should also show you what the temperatures in fact were when the code was set.
     
    #4 ChapmanF, Mar 2, 2022
  5. NoThrowningRocks

    NoThrowningRocks Junior Member

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    So if I understand you correctly, there is nothing wrong with the 420-related readings, it's simply says "abnormal" because I'm looking at it from the wrong perspective, or rather the wrong tab/section.

    I have a P0A93-346, that points to the water pump. I'm assuming, perhaps incorrectly, it's the same as the "water cooler inverter pump," which was replaced along with the catalytic converter over a week ago. The check engine light was off after

    In Step 9 of the TIS Inverter Cooling System Performance inspection process it mentions going to checking out the MG1 INVERT TEMP, MG2 INVERT TEMP and COMVERTER TEMP values. Here is the freeze frame for P0A93 and more from the data list.

    Here are screenshots for the P0A93 freeze frame and hybrid control live data.
    Freeze Frame Data P0A093 v2.jpg Hybrid Control Live Data List P0A093.jpg

    With the water inverter cooler pump already replaced, does this indicate the pump is faulty?
     
    #5 NoThrowningRocks, Mar 2, 2022
  6. ChapmanF

    ChapmanF Senior Member

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    Hmm, somehow I imagined I had replied to this yesterday, but it looks like I didn't.

    I kind of meant the opposite about the tabs and sections. The all-readiness utility is specific to "Engine and ECT" codes. That means P0420 (which is an Engine/ECT code) is a fair code to ask the all-readiness utility about, and you get a straight answer. It tells you the oxygen storage test was completed and the result was bad, and that is why the P0420 code is shown.

    It was the P0A93 code that isn't fair to ask the engine's all-readiness utility about, because P0A93 isn't a code that even comes from that ECU. So anything the readiness utility showed you about P0A93 was just the utility stammering some bogus response when you blindside it with a code it understands nothing about.

    Looking at the P0A93 freeze frame, I think it's pretty funny for a code about inverter cooling to not capture any of the inverter or MG temperatures in its freeze frame. So that's not as helpful as I hoped it would be.

    A person might then just clear the P0A93 and do some driving around, while datalogging some of the inverter/MG temperatures, and see if the code comes back, and what the temperatures were at that time. Sort of a do-it-yourself freeze frame.
     
    #6 ChapmanF, Mar 4, 2022
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