2012 Toyota Prius - P0A80 Replace Hybrid Battery Pack

Question

My Prius just hit 160k miles and the 'Check Hybrid System' light came on with the P0A80 code. The hybrid battery cooling fan is running at max speed constantly. I noticed the MPG dropped from 50 to about 38 over the last month.

I used an OBD2 app to check the block voltages and Block 6 is sitting at 14.2V while the others are at 15.8V under load. I'm wondering if I can just swap out the one bad module or if I really have to drop $2k on a whole new pack.

MountainMechMo · Accepted Answer

✅ Confirmed fix: Installed a brand new OEM Toyota battery pack. While the individual module replacement is a 'cheap' fix, the internal resistance of the remaining 27 modules was too high, causing heat buildup. Also discovered the bus bars were heavily corroded. After installing the new pack and cleaning the frame ground, the car returned to 52 MPG and all voltage deltas are within 0.1V under load.

TechTonyV · Answer

You can definitely swap a single module, but typically when one goes, the others aren't far behind. If you go that route, you must capacity-match the replacement module to the rest of the pack using a charger/discharger like a Prolong system, otherwise the Delta V will trigger the P0A80 again within a week.

2012 Toyota Prius - P0A80 Replace Hybrid Battery Pack

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