P0453 and dead battery

I thought I'd post my problem, diagnosis and solution in case it helps someone. I hadn't been driving my 2010 Prius much lately as was vacationing. It was parked outside. Started it up and engine ran, but got the ominous The "Red Triangle of Death". I expected the worst, and started researching how to rebuild my traction battery. Turns it it wasn't as bad as I thought.

Checked the voltage on the 12 V battery and it was in around 11.5 V. Put it on a smart charger for 3 days, but the smart charger never stopped charging. Car would start OK, but still got the dash warning. I pulled the battery off the charger. Next day the battery was at 5 V. Got a brand new battery ($$). Still the same problem with error on dash. Day or two later, checked voltage on new battery and it was in the 11 V range ! Oh, crap. Did I just ruin a brand new battery? Is my car going to catch fire? I disconnected the battery from the car and started charging battery up again. When it was charged up, I attached the battery to to the car and used an OBDll scanner while I started the car. (I bought a OBDLink EX because I also have a Ford.)

I got some codes that pointed to the evaporative emissions system.

Backed up the car on some ramps and crawled under to search for bad wires. Sure enough, I found the EVAP (Evaporative Emissions) Canister/Pressure Sensor sub-harness was all chewed up.



On a 3rd-generation Prius, this short sub-harness links the main chassis wiring loom directly to the components mounted on the charcoal canister assembly, which sits right above the rear subframe near the fuel tank. I pulled it off and then began the lengthy search for a replacement.

Apparently, one can't buy a new sub-harness by itself. I considered getting male and female pigtails and splicing them, but settled on getting a part from the junk yard. Cost me $50 + tax from junkyard.

Put it back on and all is good ! Now I am making a big effort to garage my dear old Prius and put mouse traps in the garage. Have to make room in the garage first.