really awful
Typical Repair Cost:
Average Mileage:
71,625 miles
Total Complaints:
4 complaints

Most Common Solutions:

  1. not sure (3 reports)
  2. dealer claimed throttle body needed cleaning (1 reports)
2004 Toyota Sienna engine problems

engine problem

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2004 Toyota Sienna Owner Comments

problem #4

Dec 012010

Sienna XLE Limited AWD 3.3L

  • Automatic transmission
  • 68,000 miles


Happened once during pedal-to-the-metal acceleration to enter busy expressway from ramp. Car full of passengers.VERY FRIGHTENING!!! Kicked accelerator pedal several times to free it. Floor mat was not the culprit, nowhere near accelerator pedal. Dealer blamed problem on me for not allowing them to clean the throttle body on previous visit. Somehow, I doubt this was the problem, but went ahead with cleaning anyway since it was less expensive than a fatal accident. Firmly believe this is part of the whole Toyota "sudden acceleration" incidents of previous years. If it happens again, will consider consulting attorney (if I survive the incident!).

- , Mont Alto, PA, USA

problem #3

Jun 172009

Sienna CE 3.2L V6

  • Automatic transmission
  • 85,000 miles

This morning I was driving another car and my wife was behind me in our 2004 Toyota Sienna van. We were heading southbound on the Lake Ponchartrain Causeway. After paying our tolls I head out first with my wife behind me. After only going about 1 mile on the 24 mile bridge I saw her pass me in the left lane at a high rate of speed. I was only going 55 mph and she must have been doing 65 plus mph. I wasn't sure what was going on. As she went further ahead I noticed smoke coming from the back of the van. A short time after that I noticed a wrecked auto in the left lane and as I looked up ahead I saw her in the van hit the right guard rail and almost plunge into the lake. Fortunately when she hit the right cement guard rail the right front tire had turned sideways due to the impact. The vehicle's engine had stopped. As I pulled up behind her she was frantic and screaming that she couldn't stop the car. She said it started accelerating as if she had floored the gas pedal. She attempted the hit the brakes as hard as she could but that didn't do anything. She also depressed the floor emergency brake and that didn't stop the van. She said she had noticed that the speedometer had only showed she was going approx. 45 mph. She said that she was unable to control the van because the steering wheel would not turn. It's as if the motor has killed and lost power steering. But that's not the case The van must have reach 70 plus mph. She ended up hitting 2 or 3 vehicles but that didn't slow her down. She only came to a stop when the van hit the right lane cement embankment and the tire and front end were damaged. It was not a case of a car mat hitting the gas pedal. It just took off as if the pedal was floored. I don't know the outcome of this since it just happened today but thank God that no one was injured.

- , Simpsonville, SC, USA

problem #2

Jul 022008

Sienna XLE

  • Automatic transmission
  • 71,500 miles

Like Mark K, my car just took off while parking. Unfortunately there was a group of teenagers standing on the sidewalk enjoying an ice cream cake when my car drove thru their little group. Fortunately, no one was killed or seriously injured. A Toyota STS looked at the car, can't duplicate the error (my car isn't drivable) and didn't find any diagnostic errors. Well, duh! My car "thought" it was supposed to accelerate. It has gone to Toyota Corporate for their review. We may have our insurance company follow up thru subrogation. It is only a matter of time before someone is killed. How many of these cars are "mom mobiles" like mine?

- , Watchung, NJ, USA

problem #1

Apr 292008

Sienna LE 3.3L

  • Automatic transmission
  • 62,000 miles

click to see larger images

sudden unintended acceleration sudden unintended acceleration

Topic: Sudden Acceleration in 2004 Toyota Sienna Van

Scenario: At 0830AM PST, April 29th 2008 I was driving to work at my school where I work as a teacher. While making a slow U-Turn, with my foot lightly on the brake pedal, my 2004 Toyota Sienna LE van suddenly took off and accelerated uncontrollably like a rocket at maximum velocity. The accelerator pedal was never pressed during this incident. I had just a split second to remove my foot completely off the brake pedal to look down at the floor board to ensure nothing was pinning the pedal downward, nothing was there and the van was still accelerating. I looked up in horror as vehicle was continuing to accelerate at an extremely high rate of speed and continuing to accelerate. I quickly steered the vehicle and dodged a screened chain-link fence to avoid an area where children usually stand waiting for parents. With vehicle still accelerating at full power I quickly passed the fence area, applied the brakes with great force, but they felt unresponsive to the acceleration forces. Now, with vehicle moving at a very high rate of speed and still accelerating, I saw a parked vehicle right in front of me and could no longer control the vehicle and I braced for impact. The van violently smashed into an unattended Ford Expedition vehicle, the engine briefly revved and then finally shut down. Had there not been a parked vehicle there the van would have gone directly into the residential house about 50 feet away. It only took about 3 or 4 seconds for the van to travel the 22 yards from where the accelerator malfunction started to the impact area of the other vehicle. In complete shock, I briefly sat there and wondered how this could have happened. Luckily I was not seriously hurt, my neck and back were sore from the impact, but other than that I was thankful that I was ok. I looked down at the floorboard again to see if anything was pushing the accelerator down. Again there was nothing there, no floor mat or any other foreign object around that area. Had this incident occurred only five minutes before, the street would have been filled with young children, parents and grandparents walking them to school. I can’t even think of how many people would have been killed or injured if this would have happened just a little earlier. Police arrived on the scene and took a statement. After a very brief visit, the police officer rudely concluded that I mixed up the two pedals and that was the cause of the accident written in his report (It should be noted that I have been driving for almost 25 years, never been the fault of an accident, never even had a ticket, and have always been rated as a A+ driver for insurance policy coverage). The police officers assessment was hasty and completely absurd. There is no way that I mixed up the two pedals but at that moment in time I was so upset I couldn’t even provide a statement and argue that the cause of the accident was a malfunction of the vehicle accelerator system. Both vehicles were then towed away and I met the vehicle at the body shop to provide necessary information.

Findings/Facts: After returning home I immediately went on the internet to see if there were blogs of any similar cases reported. After typing in “sudden acceleration toyota” or “unintended acceleration toyota” on Google I was shocked to learn that there have been many recent documented cases of unintended acceleration primarily in Toyota vehicles. These are a few of the numerous documented cases of interest:






I immediately contacted the Toyota Customer Experience Center to have the Toyota Technical Response team conduct an investigation on the vehicle. They assigned it a case number on 30 April. On 13 May I spoke with a supervisor at Toyota who informed me that a Toyota Field Technical Specialist (FTS) went to the body shop on 9 May only to find that it had been towed away to an auto salvage yard. Note that I had called the Toyota CEC almost every day trying to get status of the FTS and when he would inspect the van and they would only tell me that it will take up to 30 days to conduct the investigation. According to Toyota notes the FTS contacted me on May 1st and again on May 7th. I have call logs on all my telephones, a call was never received. Anyway, on May 8th the FTS arrived at the body shop only to find out that the vehicle had been towed away one day prior to his visit. According to the body shop representative the FTS was from the Toyota Corp Main Office (they rarely see these guys) and he really wanted to inspect this van. He inquired where it was towed to and went to track it down. Toyota case managers have not been honest with me, I don’t know if they are just unresponsive or if they are trying to cover up this issue. On 13 May I spoke with my insurance company and they confirmed that the vehicle was towed to an auto salvage yard. Currently, the vehicle is still available for inspection. I contacted the Toyota case manager and provided all the information necessary (vehicle location, stock number, etc) so that they can deploy a FTS to the van for inspection. The Toyota case manager indicated that she would call me and provide status when available. I told them that they only have about 10 working days to conduct the inspection before the vehicle is sold at auction for scrap. Time is an issue. Additional research into the 2004 Sienna van led to the discovery that Toyota implemented a relatively new technology in 2003 vehicles called the electronic throttle the uses a “drive by wire” sensor to control the throttle position. This system uses a series of rheostats, voltage comparators and sensors to determine to position of the accelerator pedal. The electronic control unit (computer) receives these signals, processes the information and sends a signal from the sensors to the throttle butterfly valve to indicate how much to increase/decrease engine speed. These vehicles no longer use the traditional mechanical cable between the pedal and throttle, it is all controlled electronically. I honestly believe that Toyota has a serious problem in this drive by wire electrical circuit that enables a faulty signal to be sent to the throttle valve that will enable it to go wide open. There have been so many cases that there is even a book by Clarence Ditlow called Sudden Acceleration: The Myth of Driver Error written to refute NHSTA findings that most incidents of sudden acceleration are caused by driver error. It accuses auto manufacturers of withholding evidence that would prove that there is a serious problem in this technology. Toyota acknowledged that they have a problem but they are blaming it on car mats. Currently, they have a massive recall on the Tacoma trucks for car mats to address sudden acceleration. In the case of my van, there is no way that car mats caused the sudden acceleration, it was clear that it was electronically driven. The NHSTA needs to take another more in depth look at what Toyota is doing to correct the sudden acceleration problem. Car mats causing all the documented Toyota vehicle sudden acceleration cases is highly unlikely.

Conclusions: On May 1, 2008 my vehicle was claimed a total loss by the insurance company. Hard to imagine that in 3-4 seconds, and traveling less than 25 yards in front of an elementary school that I could completely total a large van like my 2004 Toyota Sienna. By the Grace of God, there were no children present when this happened. Toyota has a serious problem and they are either ignoring it or simply covering it up; there is just too much information out there to dismiss it. It disturbs me to know that the NHSTA has so many documented sudden acceleration cases and yet will not conduct an investigation to pursue an in depth engineering analysis to determine the root cause. Car mat replacement provides little confidence that the sudden acceleration issue has been resolved. As mentioned earlier, if I would have been at that location 5 minutes earlier, there is no doubt in my mind that small children would have been killed, many others would have been injured, and as a result I would have been liable for it. As a parent, teacher and compassionate human being I would have been unable to live with myself knowing that I caused something catastrophic like that. This problem will not go away by replacing car mats. I hope that no one has to go through the horrific experience that happened to me, but unless someone or some organization out there uncovers this issue and alerts the public I’m afraid it’s going to happen to someone else and the results will be unfortunately catastrophic.

Recommendations: This situation will occur again to someone else. Lives will be lost and drivers will be falsely held accountable. I am not seeking any compensation for what happened I only want (plead) that the NHSTA, Toyota or some other agency immediately investigate and resolve this serious condition. In the interim, the issue needs to be raised to a high level of public awareness and drivers of subject vehicles need to be aware that sudden acceleration can occur, and if at all, prepare for the horrific event.

- , Port Hueneme, CA, USA

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