my 300000 miles prius had a blown head gasket so I had a local shop dropped in a jdm engine 2 weeks ago. After drove a couple days, everything runs good but I found that they overfill the inverter coolant by a lot so I sucked some out to the max level. Today after some driving, the "hybrid system malfunction" pop up. At first it won't let me shift to D but after couple tries, it shifted to D and drove normally despite the message, hybrid battery charged and discharged normally. I used a traditional obd2 reader and there is nothing, no code at all. Is there any way to know more detail without paying dealer $250 diagnose fee?
Buy yourself a scan tool. Read post #1 and then scroll down to post #37 in this thread, https://priuschat.com/index.php?posts/3246758 You want to buy a scan tool that is capable of communicating with all the ECUs in your Prius.
