P3102 on 2008

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by MichaelB126, Jul 6, 2026 at 11:30 PM.

  1. MichaelB126

    MichaelB126 Junior Member

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    Hey Folks.
    I've scanned the forum for my code and have gathered it can be a bunch of things.
    Here's what I've done recently changed fuel injector, had one sputtering. Changed plugs and coil packs.
    Had the battery and alternator tested at parts store, both are good.

    No other codes came back using Dr Prius.
    Used multi meter to check the voltage, was low at 5 volts. Charged to 13 and drove next day for 50 miles (one stop with engine off for an hour) and on way home I got the infotainment warning to park on level ground and use parking brake. Charged again then went to parts store to check battery and alternator.
    I saw in a post there are 7 sub codes w 3102.
    Anything else I can check?
    Any guidance on a good scanner thats not $500?
     
    #1 MichaelB126, Jul 6, 2026 at 11:30 PM
  2. PriusCamper

    PriusCamper Senior Member

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    But until you got a solid 13v (14.1v in ready mode) from a fresh charged battery chasing codes is a waste of time.
     
    #2 PriusCamper, Jul 7, 2026 at 1:28 AM
  3. pasadena_commut

    pasadena_commut Senior Member

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    I wouldn't trust a battery that had been discharged to that voltage. It might charge up to something reasonable, but it is probably heavily sulfated.
     
    #3 pasadena_commut, Jul 7, 2026 at 1:54 PM
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  4. bisco

    bisco cookie crumbler

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    get a free 12v load test at most auto parts stores
     
    #4 bisco, Jul 7, 2026 at 2:03 PM
  5. bisco

    bisco cookie crumbler

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    #5 bisco, Jul 7, 2026 at 2:05 PM
  6. MichaelB126

    MichaelB126 Junior Member

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    Borrowing a topdon AD500 scanner and battery charger with desulfating mode.
     
    #6 MichaelB126, Jul 7, 2026 at 10:17 PM
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  7. pasadena_commut

    pasadena_commut Senior Member

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    I'm highly dubious about desulating modes for AGM batteries. Most of those charger modes are for conventional flooded lead acid batteries. Some of the chargers with pulsed desulfating modes claim to work on AGM, but you would have to wait weeks or even months to find out if it made a difference. Since the same manufacturers almost never provide any evidence to support those claims take them with a spoonful of salt. There are of course many anecdotal claims of success - just as there are with every brand of liquid snake oil.

    Edit. I wasn't sufficiently clear. DO NOT use a desulfating mode intended for a flooded battery on an AGM battery. Any of the high voltage or high current methods is going to damage the AGM battery as there isn't enough fluid on the plates to support those extreme conditions.
     
    #7 pasadena_commut, Jul 8, 2026 at 1:27 PM
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