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Potentially bad ecu?

Discussion in 'Gen 2 Prius Main Forum' started by Priusprofit, Aug 11, 2018.

  1. Priusprofit

    Priusprofit Member

    Joined:
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    Vehicle:
    2005 Prius
    Model:
    II
    Hey PC, I've got a 2005 prius with an issue peculiar to me.

    I have code for downstream oxygen sensor p0137 ( I have replaced twice and code still comes back and shows a reading of .01- .035 volts while upstream sensor is reading 2.5-3.5 volts.

    Other issue is at random between 5-50 miles after code reset the engine starts running very poorly and throws p3190 for "poor engine performance" and car either doesnt move or only runs on battery. After erasing code it will run again half the time, the other half the time I need to disconnect 12v battery to drain memory completely.

    I have recently replaced manifold, both o2 sensors and catylitic converter.

    Next step I believe is to replace ecu ecm in Hope's that it is causing both problems. I have 3 and its somewhat likely I'll even have the matching part number. Besides the physical replacement is there any additional steps in programming it? And does it sound like it could be the problem?

    Posted via the PriusChat mobile app.
     
    #1 Priusprofit, Aug 11, 2018
  2. bisco

    bisco cookie crumbler

    Joined:
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    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
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    Plug-in Base
    wow, how many miles on her?
     
    #2 bisco, Aug 11, 2018
  3. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Two
    Which manifold did you replace - intake or exhaust? If intake, did you use all new gaskets? Is the hardware properly torqued? Look for intake air leaks downstream from the mass air flow sensor: the clamp attaching the bottom of the engine air cleaner housing to the throttle body, the gasket between the throttle body and the intake manifold, and the gasket between the intake manifold and the cylinder head.

    Regarding DTC P0137, I think it is possible that you have a wiring harness problem between the downstream O2 sensor and the engine ECU.

    Regarding P3190, look at the throttle body interior. If it is dirty, clean the throttle body interior and throttle plate using a clean cloth moistened in throttle body cleaner fluid. Do not drown the throttle body in cleaner.

    The engine ECU is the last item that I would change, not the first.
     
    #3 Patrick Wong, Aug 12, 2018
    Dxta and Raytheeagle like this.
  4. Priusprofit

    Priusprofit Member

    Joined:
    Mar 2, 2018
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    Location:
    Long island
    Vehicle:
    2005 Prius
    Model:
    II
    Only 264k miles

    Posted via the PriusChat mobile app.
     
    #4 Priusprofit, Aug 12, 2018
    bisco likes this.
  5. Priusprofit

    Priusprofit Member

    Joined:
    Mar 2, 2018
    96
    32
    0
    Location:
    Long island
    Vehicle:
    2005 Prius
    Model:
    II
    The exhaust manifold was replaced, new donut and spring bolts. I will try my best to inspect that harness, I am not a pro with automotive wiring. I have checked once and did not notice any leaks so I will inspect the throttle body. Thank you for your input!

    Posted via the PriusChat mobile app.
     
    #5 Priusprofit, Aug 12, 2018
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