IMy prius has 612/526 code. I have 2 questions 1. Is it always the hybrid battery? Can it be something outside battery too? 2. If it is hybrid battery, I have a spare in my garage. It was pulled from a totalled prius, bought at junkyard. But it has been sitting there for about 5-6 years. Is it still usable or would it have degraded to a point of no return? If old battery is not usable, what are some tips to diagnose the 612/526? I have the pdf, but it is a bit daunting, and wanted to know if there are some common things ( I read somewhere about "goop on the bottom" that can be wiped clean) that I should look for before getting into full blown diagnostics. At the end, is it worth all this or just buy a reconditioned battery and hope it will last few years? Thanks in advance.
Is this the same car that you created a thread about in August 2025 that had trouble code P0AA6 and sub-codes of 526 & 612? https://priuschat.com/index.php?posts/3560310
Yes it is. Had a family crisis and couldn't tent to it for a while. Recently I started it (had to charge 12v battery, everything reset) and it ran fine for about 250 miles before triangle of death came back. It is 2006 prius with 176k. I was cleaning garage yesterday and came across.the battery that has been sitting there and thought there might be an easy route.
If you have the equipment to reconditioning the old battery modules it may work, but it will be a long time consuming process. Posted via the PriusChat mobile app.
Thanks. I don't have reconditioning equipment, may have to find a local service person. My car DIY skills are limited, but considering the cost, I am willing to open the hybrid battery. Is there a way to know it is the battery and not something related to inverter or something else before taking battery apart? Or is it battery most of the cases?
With the appropriate OBD2 dongle, phone/computer, and software you can read the battery module voltages and resistances. (Actually they are read in pairs, so 14 values rather than 28.) If some of them are very different from the others, then at a minimum there is a pack problem.
Hook up the cable, start up techstream, select the hybrid control ECU. An example of the sorts of readings which can be found are in this thread: Techstream readout, does it tell me anything? | PriusChat Note, that ECU can have corrosion on some of the pins for those sense lines, which can make the battery look bad when it is actually the ECU and the sense wires.
