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 2004 Toyota Prius owners, lightly cleaned up (personal details are redacted by NHTSA).
The contact owns a 2004 Toyota Prius. The contact stated while driving approximately 30 MPH, the vehicle stalled. The vehicle lost power steering functionality but the contact was able to safely pull off of the road. The contact stated that the check engine warning light and other unknown warning lights were illuminated before the vehicle stalled. Additionally, the instrument panel went black. The contact stated that she attempted to restart the vehicle but the vehicle would not restart. The contact had the vehicle towed to her residence and later towed to an independent mechanic. The vehicle was diagnosed and it was determined that a wiring cable connector had melted onto the battery and affected the engine. Additionally, the fuel pump needed to be replaced. The vehicle was repaired. The manufacturer had not been informed of the failure. The failure mileage was approximately 83,200.
This occurred to me yesterday while traveling 60 MPH in 94 f heat on I-76 e just before the 676 / 76 split. I was traveling in the far left lane when the car suddenly lost power. Looking at the dash I noticed the shifter had moved itself into n (neutral), it would not move back into drive. I applied my hazard lights and began forced my way rightward across three lanes to the shoulder, speed rapidly decreasing and seemingly more sluggishly than a normal coast. I think the emergency brake was automatically being applied or I was fighting a braking system. One lane from the shoulder, a ups truck was headed for me from behind. Luckily, he was able to swerve into the shoulder and pass me there as he could not move left into other traffic. We only narrowly avoided a collision with me or the elevated barrier on the side of the road. I had only 10 MPH left and no ability to redirect my vehicle. …
Tl* the contact owns a 2004 Toyota Prius. While the vehicle was in the garage, the engine started running. When the contact attempted to open the door, the engine stopped running. The vehicle was not taken to the dealer or an independent mechanic for diagnostic testing. The manufacturer was notified of the failure. The vehicle was not repaired. The approximate failure mileage was 109,000. Updated 10/27/17 the consumer stated that the vehicle was repaired. The consumer stated apparently, the vehicle was powered off incorrectly. The engine was periodically switching from gas to battery.
Tl* the contact owns a 2004 Toyota Prius. While driving 45 MPH, the hybrid system, stability control, check engine, and SRS warning indicators illuminated. The vehicle was taken to an independent Toyota mechanic who informed the contact that the vehicle needed a new hybrid coolant pump and water pump. The vehicle was not repaired. The dealer was not contacted. The manufacturer was notified and did not assist. The failure mileage was 83,772.
Warning triangle and check engine lights came on while traveling. Took vehicle to independent mechanic, who diagnosed hybrid water pump malfunction; he noted a recall, so I took vehicle to dealer. Dealer charges $130 to plug into diagnostic system, finds same problem; wants $750 to replace. Pump was replaced @ 30,000 miles ago under aon recall. Multiple reports on web about the same replacement part failing after short time.
Our 2004 Prius on four separate occasions had a complete engine shutdown with lots of indicator lights lit on the dashboard. This happened twice while we were traveling on interstate highways in traffic at highway speeds, once in a Toyota dealership while the vehicle was being serviced, and once as we pulled into a toyoto dealership for service. We were not aware we could send a complaint to NHTSA until we say today's msnbc article. The first engine shutdown occurred in the hyannis Toyota dealership in massachusetts. They took quite a while to fix the vehicle and made several phone calls to Toyota engineers for help. They wrote on our receipt: "needs trans replacement for permanent repair." after we left massachusetts we drove across country toward our home in california. The other three engine shutdowns happened during this trip. …
1. I was driving around 30 to 40 MPH and the gas engine failed suddenly during the course of normal driving, leaving only the electrical engine running. At the same time the engine failed, many lights turned on on the dashboard. 2. I was on a canyon road in the los angeles mountains when it failed, which was a single lane road each way with nowhere to pull off. Luckily, I had just reached on of the crests in the canyon when the engine failed, so with the electrical engine I was able to coast to a side street. Once on the side street, the electrical engine died quickly, probably because of the steep slope upwards of the street. 3. I tried to turn off the car and it wouldn't turn off, so I popped the hood and got out to see if there was an obvious problem. Finding no problem I could see I went back inside the car and held down the power button until the vehicle turned off finally. …
Our 2004 Prius stalled repeatedly on a drive from holland, mich., to st. Louis, mo, on dec. 26/27, 2004. The first time it happened, it was after about an hour of highway driving, when all the dashboard lights went on and the engine died. We were able to coast off the highway. After about 30 minutes on the side of the road (it was he day after christmas and a Sunday, so help was not readily available), we were able to restart the engine and return to holland. The next day, we took it to the dealer, who could not find anything wrong. We resumed driving and after about an hour, the same thing happened. We pulled to the side of the road, waited a bit, and restarted the engine. We repeated this several times, drive, stall, restart, drive, until we got to a dealer in chicago, who declared that our transmission was shot but we might as well drive back to st. …
Dt: Toyota Prius gas engine stalled 3 times, twice while driving on highway and on ramp. 1) May 13 2004 stalled in busy intersection going about 40 MPH, electrical engine still worked, so speed dropped to 20 MPH, and consumer stopped on the side. All warning lights were on. Vehicle was towed to Toyota, and they said nothing was wrong except dirty gas. They reset warning lights, and told it was safe. 2) June 1, 2004, while merging onto a highway going up the ramp at about 50 MPH car jerked and slowed to about 25 MPH without warning. Car behind m had to go onto shoulder to avoid rear ending consumer's vehicle. All warning lights were on again . When checking engine display only electrical power was working again. Gas engine had stalled, causing the immediate decrease in speed, without brake lights so car behind didn't know what was happening. Towed to Toyota. …
Nothing special or extraordinary LED up to this failure. I was driving to work at about 7:00 am. The temperature outside was about 70 degrees and the car is kept in a garage every evening. In the middle of acceleration (I was going about 25mph), the car stalled and the "red triangle of death" came up on the dash, along with several warning lights. The navigation system also provided the word "problem" and a little, red car symbol with an exclamation point in the middle of it when this happened. I was able to drive to an apartment complex under battery power only. I then shut the car off, waited a few seconds, and then started it again. The engine did kick back in after this, but the warning symbol (little, red car) on the navigation system didn't go away. …
NHTSA investigations
Engine stalling
Odi opened pe05-029 based on 33 reports of alleged gasoline engine stalling on the subject vehicles.the subject vehicles are gasoline/ electric hybrid vehicles that can be operated in gasoline or electric modes, or a combination of both depending on the power demand.all reports allege that the gasoline engine shut down suddenly without warning.some of the complainants reported that the vehicle continued to operate…
Engine complaints in other Prius years
Frequently asked questions
How common are engine problems on the 2004 Toyota Prius?
NHTSA has 98 complaints about the engine & cooling of the 2004 Toyota Prius, 16% of the model year's 610 complaints. The component named most often is engine (29 mentions).
Is there a recall for 2004 Toyota Prius engine problems?
No. NHTSA lists no engine & cooling recall for the 2004 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 2004 Toyota Prius engine problems start?
Half of the complaints with a recorded mileage happened before about 16,000 miles, and 65% before 25,000 miles.
Is it dangerous?
Owners linked 1 crash, 0 fires 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.