2005 Prius generating codes C1241 and c1300 after battery replacement

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by jesslong, May 25, 2014.

  1. jesslong

    jesslong Junior Member

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    So my check engine light had been on intermittently for the past few weeks. I thought it was for the oil change as it was about that time and ignored it.

    The other day, the 12v aux battery died. It was super old, so I figured it was time to replace it. I ordered the Optima yellow top battery. I installed it today, and it appeared to fit perfectly. I was able to start my car immediately. About an hour after starting up the car, the check engine light came back on. I was at Autozone to recycle the old battery, so I had an employee run a check on the car. It brought back codes c1241 and c1300. After researching on the forums for a bit, it seems like these are really common codes when the aux battery is running low.

    Why would I have these codes if I just replaced the battery? Was I mailed an old or malfunctioning battery, did I somehow screw up installation (I did everything myself but am NOT car savvy) or is there a bigger problem?
     
    #1 jesslong, May 25, 2014
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Both DTC were logged by the skid control ECU. C1241 means that the 12V power supplied to the ECU was abnormally low while C1300 means that the skid control ECU has failed.

    Try clearing the DTC by using a jumper on pins 4 and 13 of the OBD-II socket (do a search for the exact procedure) and see whether the warning lights come back. If they do, then have the DTC read again. If C1300 comes back, the skid control ECU has failed and will need to be replaced. That is not a minor project.
     
    #2 Patrick Wong, May 26, 2014
  3. KhaPhoRa

    KhaPhoRa Member

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    I have seen these optima batteries turn to garbage almost immediately. Yours could be another example. I have one in mine and I'm constantly checking the voltages, worried about it failing.
     
    #3 KhaPhoRa, May 27, 2014
  4. Brandonholohibrido

    Brandonholohibrido Junior Member

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    Hi if the ECU has failed, you said it is not a minor project, you mean it will cost a lot to replace it?
     
    #4 Brandonholohibrido, May 11, 2016
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Well, you could buy a used ECU which might cost $200 or less. However you would have to disassemble some of the dashboard to get to the ECU which is near the steering column.
     
    #5 Patrick Wong, May 11, 2016
  6. Brandonholohibrido

    Brandonholohibrido Junior Member

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    Ok, so you think if a prius has lower the milage from 50 to 41, new sparks, oil change, techtron additive, and still low milage, could be the sensor or the ECU? I got codes for the oxygen sensor upstream and downstream, ( sometimes I even got air fuel sensor but not this time) and I got the C1300+P0A93 (inverter cooling performance) I also have the combo meter failure, but that one just comes back during rainy days, What I care the most is to get back the milage up, you think it would be that I have to replace ECU and do the cooling fluids maintenance? I have the inverter cooling tank running at low level( not full), but I haven't seen that the fluid moves at all when I leave the car on, so maybe the water pump, could that cause the car to activate the oxygen sensor failure ?
     
    #6 Brandonholohibrido, May 11, 2016
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