Help diagnosing

Yes pretty much That's what you're going to find out You're 20-year-old battery is probably failing every time it does it sets off all kinds of other codes because other computers can't communicate with each other and it's just a round and round process of poop. This will go on and on and on and what you will eventually find is that you're probably hybrid battery is falling on its face because it's if it's original it's getting near 20 years old and if it's a refurb was probably done two plus years ago and it's failing all very typical. You can spend lots of time playing and doing things but in the end you'll spend about $1,500 bolt of battery in the trunk that's new with new cells with your computer attached to the front of it and be on your way and not look back until the ABS fails that'll be a little bit more of a project and you may get rid of the car.

 

Hello and welcome to PriusChat!

It sounds like this car has multiple problems. Misfire codes are usually unrelated to the hybrid system- most common causes are ignition system (spark plugs and/or ignition coils). Get name brand parts from a reputable source as counterfeits are a concern- esp ebay-amazon. (NGK or Denso plugs, Toyota or Denso coils)

Your other symptoms certainly could be a failing HV battery. Without codes, data, and some testing, that's just a guess. Using the Dr Prius app (along with a compatible OBD2 adapter) is a good way to monitor block voltages.

The HV battery is made up of 28 sealed 7.2V Ni-Mh modules all wired in series. The modules are grouped into pairs (2 modules = 1 block) so the battery ecu can measure the voltage- 14 blocks in all.

When a module begins to fail, the voltage of that block will go lower (often 1.0-1.5V) than the others when discharging (accelerating) and then go higher when charging (braking).

If the HV battery is at fault then repair options will depend on: budget, DIY tools and capabilities, work space, and realistic expectations for reliability.

Most $$ but good for 10+ years is to get a new set of battery modules. You can get them from Toyota and pay them to install or DIY.

NewPriusBatteries.com is one aftermarket supplier of new battery. There is also Nexpower at projectlithium.com. (you would have to install or find a shop to do it for you.)

Next are most all rebuilders or refurbishers. At best they take used modules,test then discharge and charge cycle them to improve capacity and put 28 together that have similar characteristics. At worst they take 28 random used modules and slap them in. Understand the warranty because you'll likely need it. Expect a couple years from it at most. (not recommended very often)

Find a "good" HV pack from a wrecked Prius (Gen2, Gen3, and some Gen4) and swap them in.

DIY "refurbish". Done well it can go a few years. Done poorly it might not work at all.

Rarely some here have "just" replaced the bad module(s) with used ones and have had it work. (go buy a lottery ticket!) More often the replacement doesn't match the condition of the others and the ecu sets more codes. More modules are replaced and the cycle continues. We call it "whack a mole".

Others replace bad modules and then discharge - charge cycle all the modules multiple times and test. A grid charger does all modules at once. Faster, can cost $$ for equipment. Or get multiple hobby RC chargers and do 1 module at a time (times however many chargers/channels you buy). This allows you evaluate each module separately- but takes more time.

Use the search feature as there is hundreds of threads about this stuff. Good luck.

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please post the codes, sub codes and code reader