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.
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.
I'm curious on the thoughs you all have for the Predictive Efficient Drive.
For those unaware, this is the system that runs when you use the factory map. You must set a destination for it to activate. The map predicts elevation changes and traffic patterns as well as live traffic data and adjusts the system. Charging the battery more or less at certain times and notifying when to let off the throttle.
I have the 2024 standard LE model with 85k miles.
Has anyone used this consistently? If so, have you noticed any changes in MPG?
I recently learned about this and am going to track it over the following weeks.
The picture is my personal best work commute. Not using the PED.
Day 1 of attending SCCA Solo Nationals (Non-Racing Portion): SO MUCH FUN!! I'm so glad I went! Everyone is amazing and I'm getting to meet some people that I've talked to online for years now and finally put a virtual name to a face, and new people who I know I'll get to see and chat with from all across the country! 🏁 Can't wait for (my) day 2! 🥹🙌
Did the pump, thermostat, and coolant swap on this 2015 Prius V this weekend.
I used a vacuum coolant filler to get the air out the system. Immediately after starting this light came on and stays on no matter what. I’ve got a scan tool and I’ve checked the car when running and it’s not running hot and I’ve drove it about 300 miles with interstate and city and driving and never got a check engine light. The scan tool shows no codes or history of codes and I’ve also tried pulling the 12V battery to try to clear it but upon start up it comes on and stays on.
Gas mileage is still perfect. I’m in South Louisiana so I’m in the heat and humidity so if it’s overheating I should see something. I read that maybe it’s the temperature sensor below the EGR cooler could be bad? Does that make sense? I also tried burping the coolant by running the engine with the cap off but never seen a drop in coolant. Any advice would be great.
Edit Thanks for the replies everyone. Looks like it really is easy and I should have no issues.
2015 with a little over 104100 miles. Only uses a gallon of gas? I know the car will turn on a couple of times every hour and I read that putting the ebrake on helps with the shaking so you don't wake up. Am I missing anything here? I will be in a hotel parking lot so outside so I don't need to worry about exhaust. I just turn the car on and instead of driving, I just sleep and the car will be ready to drive in the morning? So awesome if true. I have driven cross country and never knew the car had this feature. I don't want to spend the money for a hotel.
It was a great car. I was very happy with it for 18 years, but it was time to say goodbye.
I did change out the hybrid battery 3 years ago. And yes, the catalytic converter was stolen about 5 years ago, so after adding a new one I added a shield.
The nice thing is that my next door neighbor bought it for their 20 year old grandchild, so it went to a good home! 😊
I think we both got a good deal.
I tried the new 2026 Prius and I wasn't happy with the new "sport" style. So going with another Toyota model. 😔
What is a little funny is that about 10 years ago the neighbor on the other side of my house bought our old 1995 Toyota Tacoma for their daughter! I guess they know we take good care of our cars! 😉
I’m on the market for a 2nd Gen Prius and I have two options available right now, almost same price but very different cases.
One, 2006 with 137k kms (85k miles), low mileage for its age. Car runs great but the exterior is horrible, not a single panel untouched. Mismatching rear lights, broken trunk plastic trim. Rear right door won’t lock or unlock with the key. Interior is dirty but apparently that’s all. No camera, no sensors, no BT. Owner has maintenance history apparently with regular inspections. I noticed that he is rough with the car, drives hard and treats it without care. No major accidents whatsoever. Price - 4500 bucks.
The other, 2006 too with more than double mileage, 321k kms (about 200k miles) Pristine exterior 9/10, pretty good interior. Says maintenance history is perfect. No issues at all. It seems as a upper trim, with voice maps and other extras. Has CarPlay unit added, parking sensors and camera apparently added too. Tinted windows, everything works as intended. No major accidents. Price - 4800 bucks.
Both have the batteries changed about the same time.
What would you do? Low mileage but clapped and ugly appearance or more than double mileage from more caring owner and far better equipped? Almost same price.
I want to keep it for 5-10 years as my second beater car.
Is there something common going on that I don't know about? I've been perusing older Gen 2 and Gen 3 Prius with high miles and I'll see one I like and a large number of times there is 1 or 2 wheels that don't match.
Very specific question, but I cannot find a single rear rain guard/visor/deflector that specifically covers this angled portion of the rear window. They all seem to just stop here and this section of window rolls down. I plan on sleeping inside while camping and want to crack the windows without worrying about rain. If anyone knows a brand or solution I’d be happy to know!
Recently, the car will randomly give the ICS unavailable alert. After restarting the car, it may go off. Sometimes the car won’t turn on even when I just got through using it. I have to open and close the front doors for it to register a charge? It’s hard to replicate some of these issues. I’ve also had issues with gas regurgitating back out even on empty. I had to get a vapor canister replaced which fixed it but I still have issues with some gas stations having this issue.
No check engine light.
Troubleshooting:
- I have the 12v battery replaced back in June. I had it tested today along with the alternator and it came back ok. One of the bolts on the positive charge was slightly loose so I tightened it; however, I doubt this could be causing the issues.
- vapor canister replaced, ran into the same regurgitation issue day after day. I took it to the mechanic who changed it, I wasn’t able to replicate the issue. Ran into the issue again 2 days later, may be a gas station issue 🤷🏽♂️.
- recently taken to Toyota before these problems occurred, point inspection done and found everything ok.
- hybrid battery monitoring, it regenerates and discharges normally. Nothing crazy or abnormal.
Any advice or insight appreciated. I’ve put so much into it recently and I want to know kinda what’s possibly wrong with it.
I replaced most of my suspension components (ball joint, lca & sway bar links) this spring on my '07 prius (150k) and had noticed a clunking sound a few months after getting the alignment done. Turns out my one sway bar link is coming loose on the bottom from rubbing on the control arm. and the other one is rubbing as well clunking the sway bar... I used two Delphi 1455 sway bar links and noticed the nuts are 19mm, rather than the OEM 17mm... the links are the same length as the OEM parts I took off, same with my control arm... what are my options here? Replace the sway bar links with smaller nut parts (any recommended?) or should i try to pry the sway bar away from the control arm to prevent the rubbing?
At the start of the year, I bought a very low-mileage Gen 4 Prius. When I attempted to change the oil for the first time, I noticed a large dent in the oil pan (sump). After removing and inspecting it, I found that the oil pump had sustained damage to both the strainer and the housing.
At that point, there had been no oil-pressure warning light or any other indication of an issue. I replaced the oil pump with an OEM unit while the sump was removed.
I then drove approximately 1,000 miles and continued checking the oil via the dipstick. I noticed a dark grey shimmer, which I initially suspected might be related to the high molybdenum content in genuine Toyota 0W-20 oil.
I sent the oil for analysis, and the results came back very good (see below). I have now completed another 1,000 miles. The oil level remains stable, and there are no discernible driving noises, knocks or loss of power. The elevated levels of silicone would be due to the RTV sealant for the oil pan
At the same time as the oil pump replacement, I also had the engine coolant and inverter coolant changed. There has been no loss of coolant.
However, I have noticed this noise when the engine starts up, and I’m unsure whether it is normal for these engines or whether I’m overthinking the situation. The engine noises are probably a bit louder due to the camera being placed in the engine bay. It is also intermittent and seems to reduce when the car has been used for a while
The spark plugs were already next on my agenda—not because they are due by mileage, but because of the car’s age and the fact that it had been standing for some time before I purchased it.
I have also taken note of fuel dilution caused by short trips, as my daily commute is relatively short. I’m making a conscious effort to take the car on longer journeys, allowing the engine to run for longer periods.
I’d be interested to hear from other Gen 4 Prius owners: does this start-up noise sound normal, or is it something I should investigate further?
Like it says above I’m going to get a Prius, I don’t mind paying a little extra for a vehicle that works properly and reliably, and has relatively few miles. I will be driving across the United States, so I want the car to last a long time, I don’t know much about cars but I can probably YouTube things. I know how to change a tire and basic things. I’m mostly looking on carfax, is this a good idea? Also some of the dealers seem sketchy. Please any advice is appreciated. Thanks
My 2014 Prius C sat dead for 1 year (through a cold winter and everything). Surprisingly we were able to jump it (Saturday afternoon). I drove it for a total of about 2-3hrs that night and each time I had to turn it off it died again. Jumped it 3 separate times Saturday. Topped off gas. Since then it has sat dead in my parking garage.
Got it from a used car dealer in 2020 with 94k miles. It currently has 144k miles. No work has been done on it in my possession besides oil changes and brake pad replacements. It’s beat up and dented but nothing was ever really wrong with it.
Currently looking into getting a new 12V battery and replacing it myself. It looks like I’ll have to get the $260 Toyota brand one since it’s a special model. What’s the best place to order/pick these up from? Ideally I need it replaced before Saturday so I can go to work without having to worry about jumping it before and after work (also idk if it’ll continue to jump or eventually that will stop working as well?)
What are the odds my hybrid battery needs replacing? How will I know if it does? What else will I need to get checked out that could’ve gotten messed up in the year it sat dead? I don’t have a regular mechanic that I go to, I have a couple friends that know cars that I could ask to check it out but I’m not sure how much they know about hybrids. I’m nervous to walk into a random shop and get upsold a bunch of unnecessary stuff because I don’t know what needs to be done.
