Too many Error codes! 05 Prius

It sounds like you may not having a complete understanding of cells, modules and blocks as used in Techstream.

P3019 and P03020 actually means that blocks 9 and 10 are weak, not modules 9 and 10.

On PriusChat we use this terminology to keep communication good and misunderstanding low:

• Cells: are the smallest unit of the battery. The Gen 2 contains 168 cells.
• Modules: are the smallest workable unit. The Gen 2 has 28 modules comprising 6 cells. These cells cannot practically be accessed.
• Blocks: are pairs of modules and are the smallest unit monitored by the HV battery ECU. The Gen 2 Prius has 14 blocks.

Just to re-iterate, in the Gen 2, modules and blocks are counted from the right side of the battery (the opposite end from where the electrics/electronics are) to the left side (the end where the electrics/electronics are). I think you have this correct.

Techstream is telling you that block 9 (modules 17 & 18) and block 10 (modules 19 & 20) are weak. You might find one or both of the modules are actually weak. Your OCV test will only find any module with at least 1 dead cell, but not much more. Techstream is telling you that at least 2 of the 4 modules in blocks 9 & 10 are not performing within spec. So, I'd be load testing* all other modules and replacing any others that were suspect as shown by load testing. If you get more than 6 that are suspect, I'd be looking at replacing all with new (or newer i.e. < 5 yo) modules. The approach you take depends on how much time you have, how much money you have to throw at this, whether you want the repair to last 10 years or are happy for less and want to rinse and repeat. I'm told, that after pulling the battery for the third time to remediate, the novelty has well and truly worn off.

Hope that helps.



*Load testing procedure: Prolong® Battery Module Load Tester User Guide. Note the tester to which this link refers, can easily be built if you're handy.

 

You're looking at replacing at least 3 items

1. Catalytic converter
2. Hybrid battery
3. Inverter pump

And your engine might be burning lots of oil

 

OP has the right idea on the P0420 ... the fortune cookie for that code may have the word "catalyst" in it, but it would be premature to throw a cat at it before tracing the detection condition to a cause.

-Chap

 

An 05 with over 200k miles will most likely have a CAT failure.......

But if you're not in California, O2 sensor or aftermarket CAT won't break the bank. It's the hv battery that will cause problems