Code P0A0F and P3191P after 12v change

The good old failed to start and what have you codes You need to look over your ignition stuff real good look over your spark plugs every Prius I've got my hands on the spark plugs have been like hand tight in the head quite unnerving to me not necessarily going to do anything but I generally tighten them up or in the generation too since plugs can be changed easily without disassembling most of the top of the car when time permits I get the latest nip and then so plug for the car You want to check your MAF sensor clean it use a q-tip don't bend everything just clean it The q-tip is going to turn black If it's not you may not be doing it right so just get it clean he wanted maybe clean your throttle body and wipe the bottom of the throttle body out You don't have any codes for that so it's not necessarily anything going on with it but they do get oil in the bottom of them and enough can choke up things and generally wreak havoc but the MAF sensor for sure and just make sure all of your engine running gear is in good shape

 

The throttle body may be the first place to start. The car learns how far open the throttle needs to be for starting and idling, and over time as there is buildup on the throttle body, you never notice any problem, as the car just keeps learning the right new throttle position, only changing a tiny bit at a time.

But then you have some work done that involves the power being disconnected, and you hook things back up and boom, P3191, because the ECM forgot the learned throttle position and went back to where it's supposed to be when the throttle body is squeaky clean. It's a known issue with lots of reports.

So, make the throttle body squeaky clean, and it'll often start right up.

 

Yeah, if you got it started successfully and have been driving it since, it has probably re-learned the right throttle positioning for the dirty throttle body by now, and you won't be having any more issues (until the next time the battery is disconnected, anyway).

It's worth letting people know about cleaning the throttle body in these situations, because sometimes, if it's a bit worse than yours apparently was, they will never end up getting the engine started without cleaning it first, and can end up draining the traction battery trying (which is a much bigger headache).

 

Make sure to disconnect the 12 V battery afterward so that the ECU starts with the defaults. It might not need it, but it won't hurt either.