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2010 EGR replacement, now more codes then started with

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by tjohnson329, Jun 20, 2023.

  1. tjohnson329

    tjohnson329 New Member

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    I have a 2010 toyota prius with 360,000 I was originally getting P0401 an P0420. So i decided to replace the EGR and EGR cooler as well as the clean the in manifold. Once I did that I turned the car back on and got the following codes.

    P0102 - Mass air flow circuit low
    P0113 - air intake temp sensor
    P0401 - Exhaust gas recirculation flow insufficient
    P0420 - catalytic converter isn't functioning efficiently
    P0102 - Mass air flow circuit low
    P0113 - air intake temp sensor

    When I try to reset these codes with a obd2 scanner the check engine light comes right back on IMMEDIATLY.

    When the EGR was replaced I did not disconnect the 12v battery, I will be trying this at noon today. We did double check that all cables were connected properly but will recheck that as well. Any other great ideas will be helpful.

    My emissions test is tomorrow and I am trying to chug as much CRC emission system cleaner as possible to pass cause i need to renew my car registration.


    thanks in advance
     
    #1 tjohnson329, Jun 20, 2023
  2. ChapmanF

    ChapmanF Senior Member

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    The mass airflow and air intake temperature sensors are combined in one, with a single electrical connector plugged on behind the air box.

    In a big multi-step job like EGR replacement, it's pretty easy to overlook reconnecting one thing like that.

    The P0401 of course suggests rechecking your work on the EGR system.

    The P0420 might be difficult to get a passing result on by tomorrow, unless you have a source for a replacement cat today and can then drive the confirmation pattern in time for tomorrow.
     
    #2 ChapmanF, Jun 20, 2023
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  3. tjohnson329

    tjohnson329 New Member

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    THe codes were not there before the egr swap so they shouldnt be there after, cat should be fine just like the temp sensors. I am retracing all of the wiring.

    my OBD2 reader is showing the it looks like everything connected to that harness is not sending info/working. I am hoping removing the 12volt battery power for 10 minutes will work.

    I am sure One lose sensor will not cause this problem.
     

    Attached Files:

    #3 tjohnson329, Jun 20, 2023
  4. JC91006

    JC91006 Senior Member

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    you probably didn't connect everything back
     
    #4 JC91006, Jun 20, 2023
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  5. ChapmanF

    ChapmanF Senior Member

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    There are people here with plenty of experience with the same job and issues to help, but you seem to have more answers than questions.
     
    #5 ChapmanF, Jun 20, 2023
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  6. tjohnson329

    tjohnson329 New Member

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    you right, I am sorry for the way my response are wrote, not how I intended them to come out. All help is useful and thank you All for the time you took to respond.
     
    #6 tjohnson329, Jun 20, 2023
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  7. Mr. F

    Mr. F Active Member

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    There are threads here that will guide you in working through a P0401.

    However, in a recent P0401 thread a new-ish replacement EGR valve turned out to have been an aftermarket unit that seemingly did not function at all. Ensure the unit is OEM before beginning troubleshooting.
     
    #7 Mr. F, Jun 20, 2023
    Last edited: Jun 20, 2023
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