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2015 Prius 2 w/Solid 32 MPG; HV? Your thoughts?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Aps1520105, Aug 31, 2022.

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  1. Aps1520105

    Aps1520105 Junior Member

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    Hi Everyone,

    I have a 2015 Toyota Prius 2 with 77,000 miles. Over the past year I've noticed decreasing MPG from it's 50/51 mpg down to 42 MPG for several months then 36 MPG for several months now down to what seems a baseline of 32 MPG. 12V battery is fine have changed it anyway. Have also done Spark plugs and EGR/ TB/Intake Manifold cleaning with recommendations from other users. Still the issue remains with no effect on MPG. Have done Dr. Prius life expectancy test revealing a "Good" HV battery and predictive value of 74% life expectancy.

    Wondering if anyone could help me out and figure this out. Maybe you had similar issues. This is really frustrating. Purchased the car for it's great MPG which now has literally been taken away from me.

    Of note, I've noticed reduced acceleration over the course this past year. Yesterday the car was bogging down upon start up ( with low HV capacity, upper 90's heat and AC full blast) this has NEVER happened before. LOL...That was soo weird. The Bogging issue went away within 1 min of drive. I'm thinking I just need to get a new battery? Maybe the extreme heat and my stop and go city driving depleted the unit earlier than what they say batteries last?

    Appreciate your feedback

    Cheers
     
    #1 Aps1520105, Aug 31, 2022
  2. Tombukt2

    Tombukt2 Senior Member

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    Head gasket issues . Sounds like..
     
    #2 Tombukt2, Aug 31, 2022
  3. Montgomery

    Montgomery Senior Member

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    I have the same issue. If I run the AC, the HV drops fast at stop lights or sitting in a parking lot for over 10 minutes. Also been experiencing the bog down issue as well. My HV has run its course and I will be buying a new one soon after the first of the year. I had to full monty done to my car around 60k, so I know its not a head gasket, inverter thing.
     
    #3 Montgomery, Aug 31, 2022
  4. Tombukt2

    Tombukt2 Senior Member

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    Alrighty. If you know it's the battery then not much happening not much to discuss that will definitely do the trick that's the only time I ever got 36 mi to the gallon in a Prius was when I was running on the ice engine almost all the time while I was waiting for my new battery to get from Central supply to my dealer in North Carolina only two days when I drove up to the dealership to pick up my battery I was running on ice getting 36 mi to the gallon drop the new battery in and immediately was back up to 47.1 in the same tank of fuel.
     
    #4 Tombukt2, Aug 31, 2022
  5. Aps1520105

    Aps1520105 Junior Member

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    Alright, Thanks guys! Just making sure I wasn't missing anything dumb. What's disappointing is the car only has 77k on it. Will update this thread once I fix this and let you all know what happened.

    Cheers
     
    #5 Aps1520105, Aug 31, 2022
  6. Montgomery

    Montgomery Senior Member

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    Also, we are in the middle of an extreme heatwave here in SoCal. 100+ degrees daily. Killer on the HV battery.
     
    #6 Montgomery, Aug 31, 2022
  7. nicoj36

    nicoj36 Active Member

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    Change all your fluids like atf and coolants, give it a bottle of lucas fuel treatment, then do this reset. Let us know if it gains mpg.
     
    #7 nicoj36, Aug 31, 2022
  8. Tombukt2

    Tombukt2 Senior Member

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    Same here in south .near 100 90 percent humidity.
     
    #8 Tombukt2, Aug 31, 2022
  9. bisco

    bisco cookie crumbler

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    tae a look at the egr and intake manifold
     
    #9 bisco, Aug 31, 2022
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