P0A09 Code

There are two electrical wires run between the DC/DC converter (part of the inverter assembly) and the HV control ECU, carrying signals called NODD and VLO, as seen here:



The P0A09 comes with a three-digit "INF code" that some scan tools can read: either 265 or 591.

If it is 265, the ECU is complaining about what appears to be an open circuit or ground-short on the NODD wire.

If 591, it is the same complaint, but about the VLO wire.

There are separate sections in the repair manual (two or three pages each) with troubleshooting steps for solving either problem.

Toyota Service Information and Where To Find It | PriusChat

 

I've had this code before too and my question was and still is input low what input what is the input to the DC to DC converter That's low The hybrid battery voltage the 12 volt voltage or what I think when I have just a change the inverter in an '06 car or something like that to an '09 the last of the Series No problems ever since the car still running great

 

The answer is in post #2.

 

Yeah this is the one where you don't want to open the bottom of the inverter trying to get that cover off yep got it Don't mess with that quicker to just change the inverter it'll take you longer to get that cover off to the farting around in the shop you'll already have another inverter dropped in and just trash that one

 

Could be quicker yet to find out whether you have INF 265 or 591 and then troubleshoot as indicated, might even save some wear and tear on the parts cannon.