One problem related to warning light on has been reported for the 2012 Toyota Prius. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2012 Toyota Prius based on all problems reported for the 2012 Prius.
On 10-17-24 these warning lights came 1. Pre-collision system 2. Hybrid system 3. Airbag 4. Safety connect red light and intermittently: 1. Slip indicator 2. Brake system cruise control would not set, and displayed "e3". ------- component failed: dealer determined that the driver's side door harness had been chewed by a rat that had entered the under dash area "somehow". They said it couldn't be repaired but must be replaced. My insurance deductible was $500 and they paid the balance of the $1,387. 06 bill. (I have retained the harness, which could have been repaired by splicing the two wires connecting to the driver's side airbag collision sensor. The labor to splice the wires would have been less than an hour. ) ------ safety: the chewed wire apparently disabled the airbag, pre collision, emergency automatic braking, seatbelt pre-tensioning, abs, and stability systems. ----- the dealer confirmed the problem. ----- my insurance adjuster did inspect the harness. ----- I placed electronic rat traps in the vehicle, which killed three rats. ========= next ========= all the same warning lights came on a few months later! I didn't throw more money at the dealer, and took off the panels to inspect the wiring myself. There was damage to the passenger side door harness wires. I removed the harness and ordered a $60 used replacement on ebay. While waiting for delivery, I researched rat damage to Toyota wires, and how rats could possibly enter the interior of the car. I discovered that there is an unscreened 12x9 inch opening to bring fresh air into the hvac system. It is hidden under the windshield wiper cowls. Also, there are two unscreened vents in the trunk area. Other Prius owners covered those openings with 1/4 inch metal wire hardware cloth. I spent a few hours disassembling, covering, and reassembling pieces to prevent further access through the fresh air intake, and will do to the rear next. Toyota should recall these cars and ratproof the harnesses.