Which parts fail
Components named in complaints (engine, cooling system, oil leaks, timing chain, exhaust).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2009 Toyota Prius owners, lightly cleaned up (personal details are redacted by NHTSA).
The engine light went on while driving on the highway. We immediately pulled over and had the vehicle towed to the nearest dealership. The dealership informed us that both the Brake Actuator (Toyota part TO44500-47141) and water pump (Toyota par TOG9020-47031) had failed. The car was no longer save to drive.
My 2009 Toyota Prius abruptly lost power while driving. The electrical system turned off and the vehicle stalled while going 50 mph on a 2-lane parkway. While I was able to put my hazard lights on and steer the vehicle, I had no other control and was at a high risk of a crash. There's no emergency lane and few areas wide enough to pull over on the parkway. I was forced to coast the vehicle until I could pull off the parkway onto a patch of grass off the busy road. There were no warnings, messages, or other symptoms of the problems prior to failure. I had plenty of gasoline in the tank, so it wasn't due to a lack of fuel. The car would not start after pulling over and I had to get towed. …
Tl* the contact owns a 2009 Toyota Prius. The contact stated that a warning indicator flashed on the instrument panel regarding the brake system when the brake pedal was depressed. The contact also noticed smoke coming from the exhaust system. The contact inspected the vehicle and found a leak underneath the vehicle. The vehicle was taken to salinas Toyota (700 auto center cir, salinas, ca 93907, [phone]) where it was diagnosed that there was an internal brake fluid leak; however, the vehicle was excluded from the manufacturer warranty campaign. The manufacturer indicated that the obt2 sensor did not show the specific diagnostic trouble code (DTC) to receive the brake actuator replacement covered by the campaign. The dealer and the manufacturer refused to honor the warranty campaign for DTC number: c1240. The approximate failure mileage was 115,000. …
Once my car got past 100,000 miles, the non-specific warning light started coming on and the word "problem!" would come on the screen. Manual says to ask dealer what the specific problem is. Certified Toyota dealer kept saying they don't know. Turns out after my own persistence that the problem is heavy oil consumption. Not burning; not leaking. Just high consumption. Take car for regular maintenance and it seems Toyota is aware of the issue, but keeps pressing me to get a new engine, rather than offering any intermediate solutions. Could have told me thousands of miles ago to at least keep adding oil, but they never bothered. I now know after about a year that I have to start adding a lot of oil just a few weeks after the oil is changed and filled. If I wait until regular maintenance interval, all oil will be gone. …
Complete shutdown of Prius automobile with no warning while in motion on a city street. Rolled to a stop in safe area. Nothing worked except emergency blinkers. No instrumentation or warning lights appeared. The car was locked in FWD park and could not be towed by flatbed tow truck as there is no override. Lift tow truck was used to get to dealer. Diagnosed as melted hybrid invertor pump. Dealer replaced pump and fuse for a $641.47 cost to me. If this had happened on a highway/freeway it would have been a disaster. The complete loss of power without warning at freeway speed could very easily ended up as a multiple car pile up. Just the thought of crossing multiple lanes in traffic with no power, just rolling, makes me think it's time to get rid of this car.
In an attempt to avoid oncoming calves on a county dirt road driver inadvertantly pulled steering wheel to the right and hit a tree at road side. Tree is twelve inched from road surface. Before seat belt restrained driver, driver's forward momentum broke the steering wheel. Driver was not injured. Went to local hospital er. Sheriff investigated. With the extensive damage to the front end of the vehicle the air bag should have deployed. It did not. Photos taken. Your organization is being notified as we feel the air bag should have deployed. We will also contact Toyota. Thank you. [redacted]
I keep getting the code p 1121. I have replaced my engine coolant valve sensor unit three times and every single time after driving for a week the chickens and light comes on and it throws the code again. I am currently at the point where there is either no heat or it takes at least half hour or more to blow hot air. If it blows hot air it only can be on a low fan setting. I have used two different manufacturers. But unfortunately every time I replaced it same problem occurs. I have reported this in the past and there was no response. But it is occurred multiple times since. And I know there is a recall on vehicle years prior to mine.
My 2009 Toyota Prius has 100,700 miles on it. When I took it in for it's last oil change I was informed that only a little over a quart of oil drained from the engine. I have religiously changed the oil every 3,000 miles. After replacing the engine oil it still looked dirty. The engine is burning oil. I understand that this is a common issue caused by a piston design flaw and does not have a cheap solution other than adding oil at each gas fill up. I am concerned that the engine May stop working while driving, particularly if traveling on a long trip at highway speeds. I do not feel safe driving this vehicle on a long trip.
Tl* the contact owns a 2009 Toyota Prius. The contact stated that while driving 50 MPH, the engine started to rev and vehicle accelerated uncontrollably. The vehicle was restarted after waiting a movement but the failure recurred. The vehicle was towed to an independent mechanic where it was awaiting a diagnosis. The manufacturer was not made aware of the failure. The failure mileage was 65,000.
Tl* the contact owns a 2009 Toyota Prius. While driving at unknown speeds, the temperature gauge increased to high and coolant needed to be added to the vehicle. All of the indicators on the instrument panel were illuminated. The local dealer was not contacted. The vehicle was not diagnosed or repaired. The manufacturer was contacted and did not assist. The failure mileage was 151,759.
Engine complaints in other Prius years
Frequently asked questions
How common are engine problems on the 2009 Toyota Prius?
NHTSA has 26 complaints about the engine & cooling of the 2009 Toyota Prius, 5% of the model year's 502 complaints. The component named most often is engine (1 mentions).
Is there a recall for 2009 Toyota Prius engine problems?
No. NHTSA lists no engine & cooling recall for the 2009 Toyota Prius, though it has 6 recalls for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2009 Toyota Prius engine problems start?
Half of the complaints with a recorded mileage happened before about 76,000 miles, and 25% before 25,000 miles.
Is it dangerous?
Owners linked 1 crash, 1 fire and 0 injuries to engine & cooling problems on this model year. If you notice symptoms, have the car checked before driving further.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.