2019 Toyota Prius

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] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

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 and malfunctioning driver-assist systems. The most alarming part is that the driver cannot fully disable these features — the “off” button only reduces their intervention. This means when the system malfunctions, the driver is forced to operate an unsafe vehicle. As a professional rideshare driver, this problem destroyed my ability to work. Passengers reported me for unsafe driving because of the car’s erratic behavior. I eventually lost my vehicle and income. I believe this is a systemic safety defect linked to premature or unregulated implementation of AEB software. Drivers deserve the right to fully disable malfunctioning systems that endanger lives. This is not just a car issue — it’s a public safety crisis that must be urgently investigated.

The contact owns a 2019 Toyota Prius. The contact stated there was a coolant leak and the coolant level was low. There was no indication of coolant on the ground. The check engine and engine HOT warning lights were illuminated. The contact stated that the failure was related to TSB: 0135-19. The vehicle was taken to the local dealer where it was diagnosed that there was a coolant leak in the front exhaust pipe heat exchanger. The parts to repair the vehicle were on backorder. The vehicle was not repaired. The manufacturer was not contacted. The failure mileage was approximately 95,000.

Exhaust heat-exchanger coolant pipe (part of the hybrid cooling loop) on my 2019 Toyota Prius is the system that failed. Safety risk: complete loss of coolant can cause sudden engine overheating and possible power reduction or shutdown while the vehicle is moving. I transport two young children daily; an unexpected stall on a highway or during an intersection turn would put all occupants and surrounding traffic at risk. AutoNation Toyota Mall of Georgia (dealer) inspected the car on 22-May-2025, confirmed the leak, and advised the vehicle is unsafe to drive until the pipe is replaced. Repair estimate is $2,249 parts & labor to replace the front exhaust pipe that is on back order, no ETA. Toyota Corporate (Brand Engagement, Case # 250522002498) is aware; they escalated the file to their Parts Department because the replacement pipe is back-ordered with no estimated arrival date. No other agencies or insurers have inspected the vehicle. Two days before the dealer visit, the warning symbol began flashing briefly at breaking then for longer intervals while driving. On the morning of 22-May-2025 the lamp was flashing more often and longer prompting the service appointment. Dealer found the coolant reservoir completely empty. No prior warning messages had appeared.

* 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 issue is with the back middle seat belt. When the back right passenger seat, which is a 2/3 seat is placed down in order to accommodate long pieces of lumber, it remains stuck there as the seatbelt for the middle seat will not release. The seatbelt mechanism for the middle seat is located in the 2/3 seat which is stuck in the down position. Therefore, we cannot use the middle seat nor the back right seat because the seatbelt for the middle seat is locked in place and not releasing. So the back right seat is lying down and stuck there as the seatbelt for the middle seat is locked unable to release. Living alone, I rarely use the middle seat for passengers. Honestly, that seatbelt has probably only been used five times in five years. Obviously, this poses a Safety problem.