Hey I'm brand new here. Need some help!

Sure, the Powertrain Control Module is reporting the error, so it could be in the DC to DC converter, the wiring between it and the PCM, or in the PCM itself.

If the Battery is healthy and the DC to DC Converter is charging it, then it will be wiring or a PCM error. I honestly have never had the computer fail but I have never owned a Prius that long, either.

"If the engine control module (PCM) detects a drop in voltage on the auxiliary battery, it will set code P0A08.

Common Problems That Trigger the P0A08 Code

• Inverter/converter assembly failure
• Powertrain Control Module (PCM) failure
• Wiring issue" - P0A08 - OBD II Trouble Code

I am sure there are uncommon Problems as well.

Here is a blowup of the diagram in that video.


It seems to tell the A/C ECU when it can run the A/C, the HV ECU seems to warn it when voltage is low, there seems to a bidirectional control labeled NODD, I can't guess what that is. But as you can see, the actual DC to DC could work even when that all is not correct.

 

Here is the workup for P0A08 :

https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8Cpdf%E6%A0%BC%E5%BC%8F/Prius%20Service%20Manuals%202004/%E4%BF%AE%E7%90%86%E6%89%8B%E5%86%8C/04pruisr/05/21bpm/0a08264.pdf

 

The entire Inverter is about $4000 new, the DC to DC converter is about $500 new.

Prius inverter | eBay

You want one between 2004 and 2009 if you are sure it is the inverter.

 

That seems healthy to me. So you have time to fix the error, as you won't be stranded.

 

Yep, at least once, the HV ECU saw low voltage due to that.

 

You've cleared the P0420 and it continues to be thrown ?

And you aren't burning any oil at how many miles since you've taken possession ?

 

Pretty sure the dip stick measures 1.6 quarts between the two dimples. Now that you have a reference point for the vehicles oil usage you might want to check the oil more often, like once a week before you start it up for the day. Be sure the vehicle is level and has been sitting for awhile.

With that kind of oil burn I wouldn't invest in an OEM cat at this stage, maybe one of the sub $100 versions if one is needed for emissions.

Are you within a DEQ area or is that requirement statewide now?

Many have noticed increased oil consumption when driving faster on the freeway/interstate.

 

Im also new pl help
have a 2012 Toyota Prius and got the code P0A80. Was diagnosed by the toyota dealership at 170k miles few weeks ago and they said that the hybrid battery pack needs to be replaced. So i found a reputable hybrid battery shop that i have used previously as well for 2 of my other priuses before and worked great. This time i got the battery pack replaced and the codes were cleared via obd2 scanner. Car has been driving perfectly fine after the battery change “well it drive even fine with the bad battery pack”. The mpg has been decent at 40.5 to 43 depending on a/c usage. So here is the problem i took the car into a california smog inspection place and they failed the car for P0A80 “permanent code”. I went and through a few connections used a big “snap on scanner for professionals” the scanner read no current, no pending, no permanent codes and all monitors were completed for smog. Took it back to the hybrid battery shop he hooked u his “hybrid battery scanner” and determined and showed me while he hooked it up that the car has 2 ECU “1 main ECU” “2 hybrid xyz type ecu” 2 nd ecu is located in front by the passenger side foot area. ECU 2 was the one with the code stored as P0A80 and the hybrid guy said only option i have is to drive it or take it to toyota and get it flashed. Took it to miller toyota and they flashed the ecu many times and could not get the code to clear. They recommended replace hybrid battery pack. Took it back to the hybrid battery shop without questions they put in another hybrid battery. Drove the car 400 miles and still the issue is the car will not pass smog because P0A80 is stored in the ECU as a permanent code. Any help would be apprciated. 12v battery was checked to be in good condition but had it die on me this morning so i purchased a new aftermarket one. The 12v battery has 410 cold cranking amps and the other one from toyota had 380 is this a problem? Parts store said this 12v battery is made specifically for the prius.

 

I've not heard of this problem on Prius, but have heard of it on other hybrids... One hybrid re builder I'm friends with had this on a Tahoe and cleared it by doing the age old routine of disconnecting the 12v and holding the the negative and positive terminal together... And if that doesn't work my sense is the main ECU is getting a bad signal from the HV battery pack... And if they re-flash main ECU, as well as swapped packs the problem is somewhere in the wiring between the hybrid pack's ECU and main ECU.

 

Ok so should i check voltage on the wires in bewteen? Do you know how many ecu’s the car has by any chance? I think it has two one by the passenger side foot well and another in the front?

 

Visually inspecting for damage in those wires is first step... Testing them is a whole other can of worms... Also, I've the suspicion that something is missing from this story, some vital piece of information is being left out.