Cat theft, check engine, and red triangle

I live 20 minutes south of you... Those warning lights store error codes that point to what the problem is. My best guess is that while your car sat for a while awaiting a replacement catalytic converter you're hybrid battery discharged to the point of throwing warning codes and computer shut down the hybrid system to protect it.

You can clear the codes by disconnecting 12v battery for a few minutes. You can also try to force charge it by putting the car in drive, left foot on brake, right foot floors the accelerator.

Also for less than $30 you can buy an OBD2 code reader that plugs into the car that will allow you to use a phone app like Dr. Prius app to read and clear those error codes and subcodes. Here's a buyer's guide: Hybrid battery diagnostic and repair tool for Toyota and Lexus

Alternatively if you stop by my place I can do that for you...

 

Are you sure you've got the wiring right on the denso sensor?
You can get the Denso one. Works fine but the wires are a different colour.
I stripped them and joined it inside a plastic junction box.
The 2 whites go to the blacks on the denso
The black goes to the blue on the denso
The grey goes to the white on the denso

 

Apologies.
I assumed that since they took the cat, they must have cut the wires on the sensor.

 

So I drove to OP's house last evening and loaned him an OBD2 reader and showed him how to read and clear error codes and keep an eye on temperature via Dr. Prius app so he can get a little more life out of his battery pack before he pulls it and works on it.

He's an ideal candidate to rebuild his own pack as he's experienced with DIY car repairs and recently bought a B6 SkyRC type charger to successfully repair a dead vacuum cleaner robot he bought for $10. So I'll be hooking him up with a replacement module or two and others on here who have pack rebuild experience can be helpful with this process too.

Here's screenshots. The voltage difference when car first started but before I grabbed the screenshot was 1.34v, s he definitely has one or more bad cells.

 

The thieves usually do cut the wires, but those exposed wires are part of the sensor. The connector is inside the car. So you unplug the old connector and cut wires- install the new sensor and pass the new connector through a hole in the floor and plug it into the vehicle harness.

Posted via the PriusChat mobile app.

 

P3000 is simply detecting the brief voltage difference in block #9 because of bad cell... The fast charging and discharging is a sign of lost capacity, usually down to 50% capacity at this stage. Here's the science of it: BU-807: How to Restore Nickel-based Batteries; Battery University

Here's the FAQ for a charger/discharger system, which because of your electronic experience you can build yourself via @alftoy who is currently building one for less than $100: FAQ (Frequently Asked Questions) | Hybrid Automotive

Will offer more details tomorrow.