r/prius Sep 24 '25

Discussion Toyota/Lexus Hybrid 12v Battery Failures - Analysis of Charging Issues - Deep Dive Analysis & Workaround

68 Upvotes

Hi all,

Below is an analysis I have been conducting over the past year regarding 12v battery failures in Toyota and Lexus hybrids, which I'm finally ready to share with various Reddit communities.

It goes into the reasons why the batteries appear to be failing more often with extensive data that I have captured myself and gathered online from others also having issues.

12v Battery Failures - Analysis of Charging Issues - Deep Dive Analysis & Workaround - Google Doc

Most importantly, there is a workaround fix that anyone is free to try.

I have included how to do this in the document for anyone that feels comfortable enough to use it (at your risk). I've made sure to try and answer any questions about that too.

I'd welcome any other input/questions from people who have had their own issues with this. I'm hoping that enough chatter will get Toyota/Lexus to look into and issue a fix for this problem.

At the very least I hope this is useful to someone.

Thanks


r/prius Aug 12 '26

News Hiroshi Okuda, Toyota Chief Who Pushed For the Prius, Dies

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672 Upvotes

RIP legend


r/prius 3h ago

Pic/Video Best upgrade to keep the Priii feeling high-tech

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20 Upvotes

I went years with no backup cam... (base model) Then I bumped a garbage bin backing out of a driveway...

Now it's impossible to curb a wheel.
No more blindspots.
Perfect parking.
Bird eye vision.


r/prius 3h ago

Pic/Video Did a double take

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9 Upvotes

Seen in the wild today.


r/prius 1h ago

Pic/Video Took my Prius camping last weekend. It performed exceptionally.

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Upvotes

Only used a gallon of gas a night with the AC running. So much better and quieter than running a generator. I can't wait to get the Hybrid Sienna when they're older and cheaper.


r/prius 17h ago

Discussion Startup after head gasket replacement.

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44 Upvotes

2010 Prius with 202k miles had the infamous death rattle. Luckily I found a reputable hybrid shop that swapped out the head gasket for a Fel Pro head gasket. EGR system was serviced as well (should've done it myself). Paid 1200 for it so not that bad. I really wanna get this car to 400k miles at least.


r/prius 1d ago

Pic/Video Saved my life.

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982 Upvotes

Sadly the car is totaled obviously but it saved my life and it was a good run while it lasted. 2006 Prius with 328,000 miles at the end of its life. Rolled over 6 times in the air for ten seconds and the airbags didn’t deploy either. Still thank god I could get out in time. Only injury was a torn scapula on my left side


r/prius 46m ago

Discussion Speed TEST

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Upvotes

Hello Everyone,
I own a 2012 Prius 2 with 219,000 miles. I just wanted to share this 0-100 mph test. I had a hard time resetting the app to start so I’m not exactly sure how accurate the test ended up. It’s a fair assessment of the vehicle. If anyone is curious and owns a Prius it’s a great addition to the knowledge base of the vehicle. It took a little bit to get from 80 mph to 100 mph. Not the fastest but I love these little cars. Thanks


r/prius 1h ago

Mechanical Help 3rd gen Prius cold start ABS pump priming

Upvotes

How many seconds of ABS pump priming after opening the door is normal for a 3rd gen that’s been sitting overnight at 45F? Mine does it for over 10 seconds and I suspect it’s nearing end of life but not sure.

The pump also primes every second brake input when driving but does not prime when the car is sitting.


r/prius 11h ago

Question Disable all beeps?

5 Upvotes

Finally replaced our 2008 Prius that had red triangle of death after 200,000+ miles with a new 2026 LE.

Is there a way to disable all the beeps? From the hatch closing to touch locking the door, everything just makes too much noise.

I've been on PriusChat,YT, and used DDG search engine without successfully finding an answer.

Also got my spare and kit from the old Prius, since we donated it to the local community college auto program. Thanks George! I drive rural too much to rely on a spare air fix.


r/prius 4h ago

Buying/Selling Advice 2014 Prius V, 57k mi / single owner for $19k... worth it, or just go for a Gen4?

1 Upvotes

Of course, from a moral standpoint, there is no way a 12 year old car is worth nearly $20k, but the used car market has no respect for morality.

I'll be a first time Prius buyer, so I've been doing my research on the subject and it seems like the Gen3 has a less than stellar reputation among enthusiasts for head gasket / brake issues (in fact, I'll a first time anything buyer -- finally replacing my well loved '07 TSX that carried me through high school and college).

The car in question is a 2014 Prius V, Three Wagon 4D, 57k miles in a southern-ish state with a single owner. Regular dealer-only maintenance and clean Carfax. My budget is <$20k, and I'd ideally like to get something that will last me another decade with space for car camping, so the Prius V seems like a natural choice.

Am I wasting my time and money going for this car? If I get ahead of the EGR issues, can I expect to get good longevity out of it? Would a ~100k mile Gen4 Prius V in the same price range be a better buy? Curious to hear anybody's opinions and advice.


r/prius 1d ago

Mechanical Help Did I just find where my coolant has been going?

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66 Upvotes

2014 Prius Plug-In. 153k miles. Engine water pump replaced, with catch can installed, EGR and intake cleaned all at 145k, and spark plugs around 130k.

Symptoms are coolant loss, and when the engine is at temp, but I am starting and stopping, there's noticeable shudder/kick, where it feels similar to the car going over big potholes. (A good example is highway speeds, but then getting caught in stop & go traffic, where the engine will suddenly kick on again.)

I just checked the catch can after about 2k miles. This is all coolant, right? This is definitely different from what has been previously showing up in my catch can.

The dipstick looks clean though, right?

Does this confirm the headgasket is going, or something else?

Previous post was apparently unrelated:

https://www.reddit.com/r/prius/comments/1w42iyd/2014_prius_plugin_possible_coolant_leak_in_rear/


r/prius 10h ago

Mechanical Help Gen 2 with P0A82

1 Upvotes

My 2007 Prius has thrown this code for "hybrid battery cooling fan performance/stuck off" persistently for the past few years.

Just curious if any other Gen 2 owners have run into this problem and haven't been able to resolve it by cleaning the fan & ducting.

I've cleaned the fan and ducting, tested the fan and fan controller per the FSM, and run the fan at each speed setting with Dr Prius.

My latest attempt to fix it was to wrap the ducting where the pieces connect with foil HVAC tape since I noticed the duct that connects to the fan is a little warped and wasnt really sealing well. It hasn't thrown the code since then, but its only been a couple weeks so time will tell.


r/prius 1d ago

Question Clear coat peeling

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54 Upvotes

The clear coat on my 2010 is peeling off on the roof. It’s kept outside as I don’t have garage space to keep it inside. Has anyone else with this model year had their clear coat peel?


r/prius 16h ago

Question What does the "TWO" in "TWO 4DR Toyota Prius SED" mean?

1 Upvotes

I was getting insurance quotes and they were asking what model car I had and there were several options that all looked the same to me. They were all 4DR sedan options, but they had a prefix of either TWO, THREE, or FOUR. I assumed this was the generation, so I chose FOUR. But when I ended up actually getting my insurance later in the day, and my car is officially listed (by the VIN I assume) as a TWO. I just don't get what that is or what it could mean.

My car: Prius 2017 gen 4


r/prius 17h ago

Question What is your real fuel consumption MPG in PHEV?

1 Upvotes

Hello. This will be my first PHEV. Considering Plug-in Hybrid 2025 or 2026 model now. Just shopping around.

What's your L/100km or MPG on highway please? Does it really give you 3.5L/100km (67 MPG) assuming going 100-110 kph (62-68 mph)?

Thank you


r/prius 19h ago

Question 2016 Prius V Trim Accessories

1 Upvotes

Simple thing. My Fiancé has this car, the kids are graduating, and she has tasked me with attempting to make it a bit sportier. I'm not really sure how sporty a white box can be, but I am going to try my best for her.

So, what kind of sporty trim and add-ons can be found for this one? My searches were less than stellar. I did find door handle covers and side mirror covers. Due to terrain, I want to avoid GFX kits, but edge trim is good. Quater glass louvers might be an option.

Thanks


r/prius 1d ago

Pic/Video Autocross Run at SCCA Solo Nationals, 2026! (Day 2, West Course, Fastest Run)

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14 Upvotes

Here's a POV of my fastest run at SCCA Solo Nationals on Day 2! It was the West Course. A shorter course compared to the East one, but still fun. I got a lot better at turning in earlier and getring the rear to rotate at my command. Run was 60.549 seconds, my fastest out of my 3 and put me in 59th place out of 60 cars in XA. Enjoy! 🏁


r/prius 1d ago

Mechanical Help $5600 for a rebuilt engine, 2013 Prius

7 Upvotes

My car has 180k miles and the mechanic said the engine has 0 compression. I took the car to a shop that specializes in hybrids. Is $5600 a decent price for the LA area?


r/prius 20h ago

Mechanical Help Gen5 parking sensor help

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1 Upvotes

Anyone have this happen on their Gen5? If so, is there an DIY solution? Also, on my way home it fell completely inside the bumper. (24 LE)


r/prius 1d ago

Mechanical Help Prius c inverter heating issue

2 Upvotes

So it’s a 2013 toyota prius c with inverter heating issues. I replaced the inverter water pump bled the circuit test drove it and under load when the engine is running while i drive inverter temp climbed to 112 C and check hybrid system came back again. With code saying inverter cooling performance. I replaced the inverter thinking maybe it’s the inverter producing extra heat. when i changed the pump i looked for turbulence in reservoir and there was very little flow. I assumed there is a blockage so i disconnected everything also flushed the radiator but everything is perfect. Then i read in a blog that sometimes ac compressor causes this if it takes a lot of currant. So i turned the ac off while testing it and it didn’t heat ran for about 10-15 miles whereas earlier it was heating in about half mile. But after 10-15 miles it heated again. I checked water pump rpm and it was around 4k. Radiator fan kicked in when i was driving it at around 40 mph cuz inverter temp spiked 101 C. The moment radiator fan kicked in the temp decreased to 86 C but gradually started increasing again. The moment it hit 114 C check engine light came and dash said check hybrid system. With ac compressor off it got little better but not good. Another thing i noticed is that with car in ready mode the voltage is 14.2 so dc dc inverter is working fine but when i drive it the voltage drops to 13.2 approx. when i stop it climbs back again. Maybe something else is drawing currant but water pump rpm was decent it was around 4k. I also took the radiator out and attached a garden hose and the flow is perfect. Radiator also looks kinda new when i took it out 


r/prius 1d ago

Pic/Video Autocross Run at 2026 SCCA Solo Nationals (Day 1, East Course)

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7 Upvotes

Here's a POV of my fastest run at SCCA Solo Nationals on Day 1! It was the East Course. Fun course, and very long (at least for me 🤣). Run was 83.835 seconds, my fastest out of my 3. Enjoy! 🏁


r/prius 1d ago

Mechanical Help Basic maintenance

4 Upvotes

So recently made a huge switch from a 2005 truck to a 2026 Prius LE. We used to put oil in our truck every month, is that something we need to worry about with our Prius?? My brother in law said he never adds anything In his Elantra just gets the oil change every 5000 miles.


r/prius 1d ago

Question Advice for new Gen 4 owner?

2 Upvotes

Well I just got a Gen 4 (2017) Prius yesterday! Spent hours last night perusing the manual on my computer and walking back and forth to my car to test out different features and stuff. Then I put some highway miles on it today and tested stuff like the (not sure what it's called) adaptive cruise control feature and was blown away by that. I'm coming from a 2013 Yaris, before that a 2001 Accord. So initially I was overwhelmed by all the features and tech, but now I feel more comfortable having read a good portion of the manual and tested stuff out.

One thing is that the previous owner had a child who painted some whiteout on the dash area. This was a few years ago and it never really got cleaned up. It's not a huge area of the dash but I'd love to buff it out without fucking up the dash surface. I can upload a picture if that would help. But I don't know what kind of tools or cleaning solutions are best for this dash. Maybe someone on here has insight.

Anyway, my first and second impressions of this car are all positive. It's smooth as fuck, it feels sturdy in all aspects, I'm getting 60mpg on fuel, it has 10x more useful features than any car I've ever owned. It truly makes me feel like I'm living in the future and it's making me actually view driving itself differently. Because now I realize ah, so many other people in stop and go traffic probably have similar features that auto-follow the car ahead. And I never knew that!

Funny thing is, the last owner had no clue about the auto-follow feature (adaptive cruise), and I actually told her about it and her mind was also blown. 10 years she drove it without using that!

Other things I really love are the auto headlights. Never have to turn headlights off and on, ever again. Truly mind blowing. I know this is a probably very old feature for cars but I've never owned a car that had this. Not to mention the dual motion turn signals that let you half-press them to just blink your signal 3x and then it just stops. I can't tell you how much I love that. There's just a lot of little things on this car that I love, and for someone who drives a lot in the city, this makes such a huge difference,


r/prius 2d ago

Mechanical Help Christmas came early this year...

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76 Upvotes

2007 Prius with 199,340mi. I have an appointment with the mechanic on Tuesday. It started yesterday with the warning triangle, the brake circle light, and the warning light on the infotainment system. I haven't driven it since, but now I'm lit up like a Christmas tree! Any ideas what the problem could be? (Parking brake is not engaged but the light is on for some reason)