2015 Toyota Sienna engine problems

Filed Aug 26, 2026 · Engine · TX

Component Failed & Availability: The engine on my 2015 Toyota Sienna (99,000 miles) catastrophically failed and is completely seized. The vehicle and engine are in my possession and are fully available for physical inspection. Safety Risk: The vehicle shut down completely while in motion, causing an immediate loss of motive power, power steering, and power braking assistance. Had this un-warned seizure occurred at highway speeds rather than a parking lot, the sudden loss of vehicle control would have posed a severe crash hazard. Reproduced/Confirmed: Yes. A certified mechanic removed the serpentine belt, attempted to turn the engine with a lock bar, and confirmed the engine block is completely seized. The local dealership, Fred Haas ToyotaWorld, also confirmed the vehicle does not run. Inspections: The vehicle was inspected by my independent mechanic and the local dealership. However, Toyota Corporate formally refused my request to dispatch a field engineer to inspect the defective engine. Prior Warnings: There were absolutely no warning lamps, check engine lights, temperature spikes, or abnormal noises prior to the failure. The engine seized instantly and without warning.

Filed Jul 17, 2026 · Engine · NJ

I am submitting this complaint to request that the federal safety agency document and evaluate what may be a broader defect affecting certain Toyota Sienna vehicles and determine whether it presents a potential safety-related defect trend. My 2015 Toyota Sienna was diagnosed by an authorized Toyota dealership with an external rear-bank head gasket leak. A head gasket is a critical engine component, and failure can result in coolant loss, engine overheating, reduced engine performance, stalling, or complete vehicle disablement. These conditions may create a safety risk, particularly if they occur while driving in traffic or at highway speeds. An authorized Toyota dealership confirmed the diagnosis and submitted a goodwill assistance request to Toyota. The dealership noted my history as a repeat Toyota customer and recommended that assistance be provided. Toyota denied the goodwill request based on the vehicle's age and mileage. I subsequently appealed through Toyota's customer relations process, and the denial was upheld. I understand that the federal safety agency does not resolve individual warranty or customer-assistance disputes. My purpose in submitting this complaint is to request that the federal safety agency determine whether similar reports exist involving premature head gasket failures in this model year or related vehicles and, if warranted, evaluate whether a broader defect trend exists that could present a safety concern. Potential safety consequences include engine overheating, loss of power, stalling, and unexpected vehicle disablement. The vehicle has been maintained in accordance with manufacturer recommendations and has not experienced any overheating event that would reasonably explain a premature head gasket failure. Thank you for your consideration and for documenting this complaint as part of the federal safety agency's review of potential vehicle safety issues. Respectfully, Vehicle Owner

Filed Feb 6, 2026 · Engine · NJ

i am having repeated issue with Toyota sienna engine 1. Engine oil leaks through timing chain cover 2. Engine coolant leak Engine oil leak keep repating even I fixed earlier and leaks again due poor engine design same issue fixed on Nov/22/20 - 59k

Filed May 12, 2025 · Engine · TX · fire

My engine caught on fire. We had seconds to get out prior to it engulfing in flames. Fire department had to extinguish. Not sure what caused it. The entire vehicle caught on fire. There was an engine light warning I had the vehicle repaired but the warning light was not cleared

Filed Feb 22, 2024 · Engine · MA

The intake valve became burnt/stuck, causing my car to lose all compression on cylinder 3. The CEL came on, flashing, and the car immediately started driving rough and not accelerating. I had the vehicle brought to 2 different auto shops that confirmed the issue. My and my childrens' safety were at risk as soon as we tried to turn right onto a high speed road and my car started the flashing CEL and would not accelerate. There was no warning before this incident.

Filed Nov 15, 2021 · Engine · 87,000 miles · MI

The contact owns a 2015 Toyota Sienna. The contact stated while starting the vehicle he noticed that the vehicle was shuddering and shaking uncontrollably. The check engine warning light was illuminated. The contact attempted to restart the vehicle however, the failure persisted. The contact took the vehicle to an independent mechanic to be diagnosed. The contact was informed that the failure was due to low cylinder pressure on cylinder #6. The mechanic was not able to do the repair on the vehicle, so the contact took the vehicle to the local dealer who diagnosed and confirmed the failure as a misfire and low-pressure cylinder #6 and that the spark plug was damaged. The vehicle was repaired however, the failure persisted. The dealer recommended that the engine be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure. The failure mileage was approximately 87,000.

Filed Jan 26, 2021 · Brakes, Electrical · 50,000 miles · NY

Sliding doors are pone when car is un montn, this problem will cause a fatal accidents,the water pump has a defects.

Filed Mar 5, 2020 · Acceleration, Engine · 48,000 miles · MA

My sienna van sometimes responds very late to acceleration. This becomes a problem on highways specifically during the merging. Acceleration paddle has to be pressed very hard, for first few seconds there is no response from engine then latter it suddenly accelerates. This makes you miss judge the time required to merge on highways and can cause accidents. This has been happening since few months. I am providing tentative date below.

Filed Jan 27, 2020 · Engine, Fuel system · 36,650 miles · WA

When the car is at idle speed, such as waiting for traffic to clear for a left turn, the car will just die without warning. It will usually restart right away, but this has nearly caused a collision. The dealership in bellevue, wa says that's a normal thing if the car isn't properly maintained. I have brought the car to that dealership for all but one of the maintenance intervals, and the only other time was for maintenance when we were in ohio. Having the throttle body cleaned is not on the routine maintenance schedule. When the car does die there are no codes or other symbols that come up on the display, other than to say that the car died.

Filed Jan 27, 2020 · Engine · 57,505 miles · IL

Had an engine oil leak on 2015 toyota sienna. Toyota deal diagnosed and replaced timing cover gasket. Still leaked, second repair by dealer was said to be to hairline crack in upper oil pan before repair authorization ( after third repair and my complaint) dealer stated it was really upper oil pan gasket - changed story). Third repair was to replace crankshaft seal and serpentine belt. Toyota dealer stated upon third repair that the crankshaft seal was bad and had sprayed oil all over engine and serpentine belt, serpentine belt was soaked with oil and deteriorated. Would this be a safety problem is the belt broke or slipped while driving.? Any other reports of this? ".mp4" video clip available as ".mp4" 9(contact [xxx]). Information redacted pursuant to the freedom of information act (foia), 5 u.s.c. 552(b)(6).