2012 Prius V codes

I am getting a strong feeling of wiring issues in this car.

P0607 and P0037 both pertain to the ECM's ability to control heated O₂ sensor currents. Detecting whether the mixture is lean may depend on the O₂ sensor readings (though there's an A/F sensor further upstream that's probably more important for that). P261C is an issue with the water pump, but specifically an electrical issue; the tachometer signal coming back from the pump is hitting lower voltage than it should, as if it is shorting to something.

The P0A80 is battery related and I'm thinking to back-burner that for now; there seems to be all this weirdness up under the hood. Do you see any signs of rodents gnawing wires? Has somebody swiped the catalytic converter, or tried to, and left O₂ sensor wires dangling? Have you checked the electrical connections at the water pump?

By the way, per the repair manual, whenever the ECM reports a P261C (meaning it can't tell how fast the water pump runs), it has a "Fail-safe Operation" where it tells the water pump to run 0 rpm.

I have no idea whose idea it was for that to be the fail-safe operation. The other thing the ECM will do when it is reporting a water pump code is it will shut the engine right off when the temperature hits 105 ℃. That's a lower temperature than it takes to light the red-thermometer light on the dash, so all you know is the engine shut down.

It would be great to have access to Techstream, and look at the freeze frames for the codes that have been reported.

 

I would start with a 12v battery check followed by a voltage check on the hv battery. Some of your codes could be false caused by low 12v. If it is losing coolant along with the knocking, you may be right about the head gasket. For the battery checks, a bluetooth obd2 reader and the Dr Prius app would be a good $30 beginning.

 

Easy to check the fuse, but the code you've got is pretty specific.