Which parts fail
Components named in complaints (battery, alternator, wiring, ignition, instrument cluster, infotainment).
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.
During a hot period of summer, my drive selector decided to not stay in the drive position unless I held it there. I could make the initial selection of drive and then stop on the gas, but it would not stay unless I physically held the lever down in the drive position. I never had an issue with the reverse position; only drive. I could always get the car back into Park. This is an extremely unsafe driving condition because it happens without warning and the fix is not obvious. Once the driver is aware of the fix, it forces them into an unsafe driving condition: driving with one hand on the parking selector. Once cooler weather came, the issue went away. It didn't happen on all hot days and was intermittent. I replaced the drive selector in 2022 and have only had the issue come up one other time since replacing this part.
The odometer on my 2004 Prius stops at 299,999. This is a known problem in the 04-05 models that was corrected in 2006. Leaves me unable to track miles for maintenance and other uses. This also has the problem with the entire digital dash going dark which means no speedometer or gas gauge. Making the vehicle almost unable to be driven safely at this point. I have reached out to Toyota and they verify that it was an issue with this year range but because I have owned it too long they don't do anything about it
Car was in motion, 55 MPH on highway going straight, had been driving one hour. Smoke started filling the rear hatchback area, coming from the driver's side of the cargo-area floor. Pulled over and flames came up. Doused it with water. Upon inspection the sks sensor (remote control door lock sensor) had burst into flames, burning the plastic and other components around it.
Tl contact owns a 2004 Toyota Prius. While driving between 65-70 MPH, the vehicle suddenly stalled and shut off completely. The electronics of the vehicle were still operating, but the vehicle itself could not be restarted. The vehicle then shifted itself into park. The hazard lights in the vehicle began running off the auxiliary battery, which is a low power battery. In addition, the hazard lights turned off. The contact called Toyota, but they were unable to assist. The vehicle was towed to a dealer. The battery was jumped and the vehicle was restarted. A diagnostic was performed and the vehicle ran normally for six weeks before the failure recurred. The vehicle was towed to a local dealer again and they stated that there was smoke coming from the fuse box, which meant a fuse was blown. After replacing the fuse box, the vehicle performed normally. …
Speedometer & other control information display went blank. Pulled over to side of road but unable to turn off engine. Contacted Toyota & was told problem is known & warranty extend to 9 years & unlimited miles. However, my vehicle is older than nine years, so I must pay estimate $1400 to fix & car will be unavailable for estimate 2 weeks. The vehicle is unsafe to drive, prior to this known problem occurring car was operating perfectly ( averaging 50 mpg per tank of gas, documented). This appears to be a safety problem that was known by the manufacturer, however they seems to be trying to hide this by making the statistical estimate that by extending the warranty the majority of these cars would be off the road and their lawyers & legal insurance would cost less than the few humans kills after this arbitrary 9 year risk period. I could have been killed as a result of this failure! …
Contacts stated water pump and alternator stopped working twice on I'-5 towed to Toyota tacoma where they flushed fuel billed $500 car broke down on way home towed back to Toyota told charge would be 2500 to fix .. Flatbed dedicated car to bron's auto hoses and coolant system was melted payed $1500 to replace in tire coolant system and still owe 600 to synchrony car care card now returning home last week turning around to back up there was a loud crunch steering broke steering wheel crunches when turned wheels do not turn at all moving down the road called Toyota they said they fixed both on recall to fix it myself it wasn't there problem parts wore out kick rocks the parts didn't wear out they broke 5 minutes sooner id have been head on in traffic on hwy 405 instead of backing up on the city street. …
2004 Toyota Prius with HID option. One or both HID headlights go out while parked or driving. Turning the light control on and off will temporarily solve the issue. The issue is random in nature. For instance, I noticed one headlight went out this morning and before I could turn the switch to reset the other headlight went out, leaving me in the dark on the road. The vehicle May be park or in motion. There appears to be no direct relation to environmental factors. Extremely dangerous when driving on rural roads with no street lights. It appears to me to be a ballast issue. This repair requires working with high voltage components and goes beyond the scope of a diy project. This has been an ongoing issue for me, but only recently have both headlights started to fail at the same time. Thank you.
I am the owner of a 2004 Prius. After buying my car used 2 years ago I noticed that once in awhile the display, including fuel consumption, speedometer, odometer, and more, would not light up and that the car would not turn off easily several times I have been in situations where I have little gas an am unable to see my gas gauge or know how fat iam going on the highway. I understand that this was once covered by Toyota under the warranty extension but is not considered a safety concern. The warranty extension is expired. In what universe are a functioning fuel gauge and speedometer not considered a safety concern? I am also concerned that this will deteriorate further and cause an accident.
Tl* the contact owns a 2004 Toyota Prius. When the vehicle was started, the instrument panel would not illuminate. The failure recurred on several occasions. On several occasions, the vehicle would not power off after the on/off switch was depressed. The vehicle was taken to the dealer and was diagnosed that the multi functional display multi-meter and the power switch were faulty and needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure and stated that the extended warranty no longer applied to the vehicle. The approximate failure mileage was 45,000.
NHTSA investigations
Pedestrian alert sounds
NHTSA received a petition on or about July 18, 2022, requesting that Federal Motor Vehicle Safety Standard (FMVSS) 141 be applied to all electric and hybrid vehicles operating in the United States. The petition can be reviewed at NHTSA.gov under ODI Number 11486072. FMVSS 141 establishes performance requirements for pedestrian alert sounds for motor vehicles.
Electrical complaints in other Prius years
Frequently asked questions
How common are electrical problems on the 2004 Toyota Prius?
NHTSA has 177 complaints about the electrical system of the 2004 Toyota Prius, 29% of the model year's 610 complaints. The component named most often is 12v/24v/48v battery (11 mentions).
Is there a recall for 2004 Toyota Prius electrical problems?
No. NHTSA lists no electrical system 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 electrical problems start?
Half of the complaints with a recorded mileage happened before about 31,000 miles, and 45% before 25,000 miles.
Is it dangerous?
Owners linked 4 crashes, 2 fires and 1 injury to electrical system 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.