'08 Prius Won't Start: P0AFA/P3000 codes

DirkJanney_14

The HV/rear battery was replaced two years ago with a refurbed battery that has been giving me progressively lower and lower power readings over the last year. When covid lockdown kicked in, I stopped driving the car for about 6 weeks and when I tried it again in April it wouldn't start. I jumped it and was at least able to drive around with the 12v battery, but the car was basically sluggish and felt like it did before I got the HV/rear battery replaced last time.

We had a recent emergency that meant I couldn't drive the car again for about a month, now when I try to start it, I get nothing. The other day I hooked it up to another car and tried to jump it again. The car did manage to light up the dash - all the warning lights came on (red triangle, check engine, etc.) but the car would not even go into gear and when I removed the jumper cables the front dash lights and dome lights started to fade and the car was totally dead again in about three minutes. So now it won't even run if I try to jump it.

While the car was on jumper cable power, I ran OBD2 test and it confirmed the following codes: P0AFA ("Hybrid battery voltage low") and P3000 ("High Voltage Battery Fault; HV Battery Malfunction"). The "OBV Volts" reading was 13.34, but only when hooked up to jumper cables and feeding from the other car battery.

I checked the back to see if it's the water leak thing - no sign of that. I'm assuming that my front 12v battery is dead and that should now replace both that and the HV/rear battery as well. I have a service lined up that will install the HV battery, but they don't issue refunds and I'm scared that if this is not a battery issue and has something to do with the starter or fuses that I'm going to drop serious cash for no reason.

PLEASE HELP!

thecardoc3

The P3000 is just an information code that alerts the technician to the trouble in the High Voltage Battery / Controller. (This also causes the engine controller to capture a freeze frame) The P0AFA has a TSB associated to it. Toyota TSB-0166-09. The code means exactly as described, the battery cells in the Hybrid Battery are discharged. You can't start the car because the 12v battery only powers up the controls for the hybrid system and it's the hybrid battery using MG1 in the transaxle that is the "starter". In some cases, with specialized equipment that Toyota has the High Voltage battery can be charged and made operational again, but anytime the battery cells get over or undercharged it significantly shortens their lifespan, and sitting undercharged really degrades the cells.