Should I worry about the codes my obd2 reader picks up if there is no check engine light on?

Discussion in 'Gen 3 Prius Main Forum' started by N1ghtfire, Feb 17, 2021.

  1. N1ghtfire

    N1ghtfire New Member

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    My check engine light came on, I had 2 engine codes, and I did some work on my car. Replaced water pump, thermostat, spark plugs, and cleaned fuel injectors. When restarting my car after all the work it freaked out, lots of warning lights, like 10 obd2 codes, loud engine noises, engine cut off.

    After double checking the work and starting the car again, it didn't shut off and after a minute the loud noises went away and everything sounded normal. (I read somewhere that the loud noises was because the fuel injectors had air in them after I cleaned them, and after the air got pushed out the noise stopped? Is that accurate?)

    I unplugged the 12v batter for 10 minutes to reset everything, car seemed normal now and I took it on a couple miles test drive. Everything seemed good, haven't been able to drive it since because of snow. No check engine light.

    When I plug in my OBD2 and click "read engine codes" it still reads 4 different codes, I click "clear codes" and it says they are reset, but when I click "read engine codes" again they come back immediately.

    Do I need to drive the car for awhile for the codes to stop reading? Should I just ignore them as long as the check engine light isn't on?
     
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  2. tvpierce

    tvpierce Senior Member

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    What are the codes?
     
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  3. jerrymildred

    jerrymildred Senior Member

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    Clearing codes doesn't address the condition that caused the codes.

    First question to answer is if the codes you got are accurate. Most code readers don't know anything about most of the codes a Prius can generate. So, what code reader did you use? IS it Prius literate?

    Once it's clear that you're actually seeing the codes being generated, it'll depend on what they are. There are one or two air conditioning codes, for example, that pop up practically every time you read code. They have to do with the sunlight sensor, iirc.

    Chances are, if you're not getting a check engine light or a master caution, they are not a concern, but it's good to be sure.
     
  4. ChapmanF

    ChapmanF Senior Member

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    You wrote 224 words about codes you're getting (I didn't count, my computer did) without telling us the codes.
     
  5. N1ghtfire

    N1ghtfire New Member

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    I'm using the Dr. Prius app with a obd2 I got from Amazon. The Nexas Nexlink obd2

    I just now read about Permanent DTC codes and I think that's what's happening! When my car freaked out I think it caused some permeant codes and even though everything is now fixed up I have to drive a certain amount before the system erases the stored codes.

    Here are the codes I have:
    P0302
    P0113
    P0102
    P0352


    When I originally started working on my car it was because of only two codes, a P148F (replaced water pump and thermostat) and P0302 (misfire in cylinder 2, replaced spark plugs and cleaned fuel injectors)


    Is there a way to actually clear permeant codes to see if they come back?
     
  6. Grit

    Grit Senior Member

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    codes are a thing in the past. Plug in pray with new parts is the latest and greatest.
     
  7. BZzap!

    BZzap! Senior Member

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    Yep... unless you can come up with the fault codes for us, you are urinating up the hemp. Post the codes you are getting, then come back to us.
     
  8. BZzap!

    BZzap! Senior Member

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  9. BZzap!

    BZzap! Senior Member

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    Before permanent code will clear, you have to run the car through a specific drive cycle. The permenant codes are there to insure the that the car meets emission protocol before emissions tests. Simply clearing the codes before an emission test doesn’t hack it anymore.
     
  10. N1ghtfire

    N1ghtfire New Member

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    I'm having trouble finding any info on what specifically I need to do to complete a drive cycle.
    I found a post saying what the drive cycle was for a specific code (one that I don't have) and it included driving the car in different settings (like the B setting) at different speeds to complete a drive cycle. I'm not sure exactly what to do. I'm about to go on a long roadtrip and want to make sure my car is all tested and cleared before then
     
  11. ChapmanF

    ChapmanF Senior Member

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    In the Repair Manual (more info), you will find a description of what they call a "Universal Trip", plus, in various different sections pertaining to different diagnostic codes, you will find details of specific "trips" that are needed to complete the monitors for those particular codes if you have them.

    The things you have to work into the specific "trips" for particular codes usually make a certain amount of sense, if you consider what the code monitors are testing for.
     
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