2019 Toyota Prius problems

“Since October 2023, my 2019 Toyota Prius has developed severe and unpredictable driving behavior after a regular brake service, which may have triggered or coincided with a software or ECU update. The car, which had been driving smoothly since I bought it in 2021, suddenly began showing false braking, steering interference, and lane instability — as if the car were trying to “correct” problems that didn’t exist. These interventions often happen on highways or during turns, creating serious safety risks for both driver and passengers. I’ve spent months and thousands of dollars replacing parts, performing alignments, and recalibrating sensors, including at Toyota dealerships. The problem persists because it is software-based, not mechanical. I discovered that in mid–2023, the NHTSA announced upcoming rules requiring Automatic Emergency Braking (AEB) with pedestrian detection by 2029. Around that same time, reports from multiple drivers (Toyota, Honda, Hyundai, Ford, Subaru) began to appear describing the exact same issues. It seems manufacturers began silently updating vehicles to meet anticipated compliance standards. However, this introduced overly sensitive…”

“Coolant is leaking into the catalytic converter. This seems to be a common issue. Toyota issued a technical service bulletin on XXX covering this exactly. Some 2016–2019 Prius and 2017–2019 Prius Prime vehicles may exhibit low coolant level, MIL on with DTC P148F00, and/or poor heater performance due to coolant leakage at the front exhaust pipe heat exchanger. The front exhaust pipe with heat exchanger assembly has been updated. The repair is listed as a 1.5-hour remove-and-replace of the front exhaust pipe assembly, and the diagnostic procedure involves unbolting the rear exhaust pipe from the front pipe at the mating flange when everything is cold and inspecting for coolant leakage into the exhaust from the heat exchanger. The full TSB is on NHTSA's site: [XXX]”

“I was idling at a parking space and went to turn off my car. The vehicle surged forward and the BRAKE sign came on. I pushed my brake to the floor and nothing happened. I was moving toward a brick wall so I put in in reverse and the car surged backwards. The BRAKE sign came on and I pushed the brake to the floor and again nothing happened and I ended up hitting the car behind me. I immediately took my car to the dealership where they kept it for 3 days and said they could find nothing wrong and it was safe to drive. I just got it back from having the body work done and am afraid to drive it as this might happen again or worse. I am reporting it to let you know and to see if this has occurred and been reported as happening in this make and model previously. I also have 2 witnesses to what happened.”

“Whenever it rains the warning message clean parking assist sensor comes on while you are driving. Even after you clean the sensors the warning continues to beep contiously. You can press the back button but it will not stop. Also proximity sensor comes on with this incident. After the rain stops the problem stops.”

“* I was pulling into a parking space at a slow speed. When I applied the brake the car accelerated causing the car to scrape the car next to the space. The car then stopped. * The acceleration was out of my control and the brakes did not stop it. Fortunately there was no person in front of me. * The Tow truck operator who came to get the car experienced the same issue when pulling into the bay at the dealer. I do not know about the manufacturer during their inspection as they did not provide me with that information. * Toyota had an inspection performed and that report was submitted to Toyota on August 20. We just received notification from Toyota that they found no problem with the car. * No warning lights noted.”

“The contact owns a 2019 Toyota Prius. The contact stated while at a complete stop, another vehicle crashed into the rear of the vehicle and the vehicle began to accelerate unintendedly. The air bags failed to deploy. The brake pedal was depressed but failed to respond. The contact stated that he was able to prevent a crash by avoiding several vehicles while continuously depressing the brake pedal. The brake pedal responded; however, there was 62-100 ft. stopping distance delay. The contact veered to the side of the road for a moment. The contact stated that as he restarted the vehicle, the vehicle operated as needed. There was no warning light illuminated. There was no police report filed. There was no injury sustained. The contact was able to drive to his workplace. The dealer and the manufacturer were not notified of the failure. The vehicle was not diagnosed or repaired. The failure mileage was approximately 78,000.”