2012 Toyota Prius: check engine light

Filed Feb 7, 2026 · Brakes · CA

Vehicle check engine code C1391 (Antilock Brake System - abnormal leak in accumulator) came up on 2/5/2026. Recommended repair is to replace the Brake Booster Pump and Assembly, Brake Booster - over $1000 in parts alone. This WAS covered by an Extended Warranty by Toyota (10 years / 150K miles). I only have 120K miles at this time but am past the 10 year mark. However, it seems that this part will fail in every Prius given time and encourage the federal safety agency to monitor these failures and hold Toyota accountable to address post the 10 year / 150K mile mark.

Filed Nov 28, 2025 · Brakes · CA

While driving on a city road below the speed limit, braking was compromised leading to loss of traction and failure of the ABS system. During the incident, the brake, ABS, and engine warning lights all turned on and a collision was only avoided due to pumping of the brakes. Further investigation by a mechanic revealed a failure of the brake actuator system. Failure of this system has increased the stopping distance of the vehicle considerably and makes braking unreliable and unpredictable.

Filed Aug 14, 2025 · Fuel system · 137,000 miles · IL

The contact owns a 2012 Toyota Prius. The contact stated that while driving at an undisclosed speed, the accelerator pedal was depressed; however, the vehicle failed to accelerate as intended. The contact stated that the check engine and the hybrid warning lights were illuminated, and the vehicle decelerated. The contact received notification of the federal safety agency Campaign Number: 18V684000 (Hybrid Propulsion System). The vehicle was taken to the dealer; however, the contact was informed that parts were not yet available for the recall repair. The contact was informed that the parts might be available within a week. The manufacturer was made aware of the failure but provided no assistance. The failure mileage was approximately 137,000.

Filed Mar 1, 2024 · Brakes, Engine · OK

I bought my first used car, 2012 Toyota Prius, from Fowler Toyota back at the end of October 2023, but I was not able to pick it up until September 21, 2023 due to extra time for re-conditioning. I did not haggle about the price nor complained about the 3 week delay. In the last 3 weeks of owning my car, the TPMS sensor light and check engine light infrequently turned on. February 28, 2024 all the fault sensor lights on my instrument panel are on, along with the loss of proper braking function. I was not worried about the other sensor faults, but brake malfunction is a matter of life and death to myself and others on the road. I have had the car for a little over 4 months and less than 10k miles. I brought the car in to diagnose all the error codes. The dealer said it will cost over $2600 to fix the brake malfunction. I chose this particular car because carfax had well documented service records and Fowler Toyota advertised that every used vehicle for sale has surpassed rigorous inspection. I voiced my complaint to the used car director and he offered numerous default excuses for unforeseen problems inherent in buying a used car. I said I did my due diligence by selectively purchasing a used Toyota Prius, from a reputable Toyota dealership that uses a Toyota certified service center to inspect and recondition vehicles for sale. All the cliche nightmare stories of buying a used car from the side of the road car lots came true in my experience at Fowler Toyota. The worst used car story happened to me, despite performing my due diligence: to buy a used Toyota from a Toyota dealership that uses a Toyota certified service center for re-conditioning vehicles. I even paid more to finance my Prius through Toyota Financial services, which did not offer extended warranty. For God sake, I was buying a Toyota with 121k miles. I only bought a prius because I work too hard to throw away all my hard earned money on gasoline. The only recourse the dealership offered

Filed Feb 13, 2024 · Engine · PA

I was driving on the internet doing 60mph and there was a very loud bang and then a shaking of the parts under the hood. I was right next to an exit and coasted off the exit to a hotel parking lot. I had car towed to my mechanic. He said that the piston went thru the engine and the engine is done and needs replaced. I am having a hard time trusting Toyota again to purchase another Prius. I have had Prius for over 10 years and never had anything like this occur. I had no warning signs and no dashboard lights lit up until after all of this occurred and scared the life out of me then the engine light came on.

Filed Jun 18, 2021 · Electrical, Engine · CA

There has been a safety recall on my vehicle for the years 2004-2009 models of the Toyota Prius, but my model year is 2012 and I have the exact same issue. 1) My check engine light comes on and off and it appears to be the hybrid electric water pump issue related to the coolant. The cap pops off and spills out. 2) When the light comes on, I am assuming the car is starting to overheat and is putting myself and my 3 year old daughter at risk as this is the primary car we use to transport her. We have just stop taking her out at all due to this issue. When the car overheats, I pull over and it can be risky as sometimes, I am on the highway or local streets. I do not want this issue to cause problems for other other drivers as well while I am trying to pull over where ever I am. 3) The problem as I stated above has been acknowledge by you and Toyota but just for 2004-2009 models. 4) The problem has not been inspected by Toyota, the police, or third party. I have been the only person checking the car and I am using a diagnostic check engine light tool to read the code and looking under the hood to find the coolant pump leaking and popped out just as indicated in the recall for other models. 5) Yes, the check engine light and high temperature light goes on and off. The issue first appeared around November of 2020.

Filed Mar 28, 2020 · Engine · 150,999 miles · MD

2012 toyota prius ii, dealer maintained, now needs new engine due to blown head gasket. Mileage 151000. The car has run perfectly until a recent engine light came on. When it was brought into the dealership, the diagnosis was misfiring of 2 cylinders and coolant leaking into cylinders 3 and 4. There was no previous engine problems. An official complaint was filed with toyota customer service. They responded that there was no fault on their end and I should have the engine replaced at an authorized toyota dealer. A search for this trouble resulted in several other complaints of the failure of head gaskets in this year and model prius.

Filed Dec 28, 2018 · Engine · 165,000 miles · CA

Tl* the contact owns a 2012 toyota prius. While driving at an unknown speed, the check engine indicator illuminated and the vehicle vibrated. The vehicle was taken to toyota vallejo (201 auto mall pkwy, vallejo, ca 94591, (707) 552-4545) where it was diagnosed that the head gasket was blown out and the engine needed to be replaced. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was 165,000.

Filed Jul 17, 2018 · Transmission · 92,396 miles · CA

Was trying to accelerate the vehicle had no power , while driving on the street, the check engine light was on.