My Gen 2 Prius has been acting weird. What are typical symptoms of the battery going bad?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by master4g, Aug 24, 2021.

  1. master4g

    master4g Junior Member

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    Hey all. I have a 2005 Prius with 12x,xxx miles and its worked great but has been giving me some issues which I cant seem to figure out. Could it be the large battery going bad? Here is a timeline of somewhat relevant events:

    -Sep 2020: Catalytic Converter stolen. I got it replaced by didn't replace the o2 sensor. Muffler shop told me to bring it in and they would install it. Car worked perfectly without it and I somewhat wanted the "check engine" to remain so I can fail my next smog and trade in my car for $1500 as its pretty bad cosmetic condition. Check engine sign has been on since

    -Also 2020, my main screen stopped working so I cant use heater,ac etc

    -Last month: I started feeling a lack of power when I started driving. returned to normal after about 1 minute and also remained normal for the rest of the day. After about 12 hours of not driving (usually the next day) I would feel lack of power for about 1 minute again.

    -3 weeks ago. I got the dreaded red triangle, (!) and also lack of power beyond 1 minute of driving. The fan in the back right seat also turned on (battery compartment fan?) . Engine would also remain running at stop lights and with a high rev. I couldn't go faster than 30mph and engine was reving hard, like it was out of gear. I plugged in a cheap obdII reader and got codes P0037, P0138, P0606. When I cleared the codes it started driving perfectly again, no issues at all, for about 5 minutes, then red triangle returns. OBD says P0037. clearing it and lights went away and worked great again, suggesting its a software issues?

    -1 week ago: Finally got the o2 sensor and went to get it installed car drove fine for about 5 minutes with no lights, but unfortunately the red triangle returned, along with check engine, and the (!). Since my main screen doesn't work, I cant see anything on that or go into settings. However, my cheap OBDII sensor no longer finds any faults so I can't clear anything. Car drives a little better but sometimes it jumps into a high rev and remains there until I turn the car off. Rev will 3500 going 40 mph on a flat road. Once I turn the car off an on again, then it will drive normal with rev at about 1800. The battery compartment fan is also on. The engine remains running at stop lights and I'm starting to thing it has something to do with the large battery?

    Do these symptoms match with a battery going bad? I know i had a few other issues which cloud the situation a bit. When the battery is going bad, will a cheap obd2 sensor show any codes? Will a fancy obd2 reader be able to see whats wrong?

    Any direction would be appreciated. Feeling a bit sad over this. Thanks
     
  2. adrian-gregory

    adrian-gregory Junior Member

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    2010 Prius
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    Business Ed. Plus
    get yourself somewhere to get the codes read properly then you will likely have a better idea of things.
     
  3. PriusCamper

    PriusCamper Senior Member

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    This is a good example of getting stuff fixed right away and not living with warning lights, as well as not living with main screen not working because when car starts having additional problems it gets way more complicated to diagnose and cost of repair can be huge all at once rather than a little lone repair as you go over time. This is often why people will give up and find a different car, which sounds like the direction you're heading. To pull out of this nose dive, make sure you have a good 12v, get your screen fixed/replaced with a used one and confirm that your upstream and downstream O2 sensors are working well. Then once that's all taken care of we can work of the other error codes.
     
    #3 PriusCamper, Aug 24, 2021
    Last edited: Aug 24, 2021
  4. SFO

    SFO Senior Member

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    For scanning obd2 codes (DTCs), many here use a 'mini-vci' cable with 'techstream' (dealer technician diagnostic software) installed on a windows device (or emulated). Failing that, try the various free scans at each of the auto part stores, including same store different location.

    It sounds like you have a failing/failed HV battery, is this something you would want to fix yourself?

    At a minimum, have you inspected or cleaned the HV battery fan recently?

    FYI : if you've reinstalled another OEM / original cat, be sure to remove/sell it before moving on from the current vehicle.
     
  5. burrito

    burrito Member

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    That whine you're hearing the fan which cools the high voltage battery. Follow the instructions on how to clean the air intake mesh and the actual fan -- there's a NutzaboutBolts video in the sticky thread. If it's really clogged with crud (looks like dryer lint), then it won't cool the HV battery properly and it will overheat.

    This is a pretty simple thing to check/fix which could potentially fix your immediate problems.

    Also, you shouldn't clear codes just to clear codes. They represent a problem which should be addressed, then you can clear the codes!
     
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