2015 Toyota Sienna Engine Problems

I am submitting this complaint to request that the National Highway Traffic Safety Administration (NHTSA) 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 NHTSA does not resolve individual warranty or customer-assistance disputes. My purpose in submitting this complaint is to request that NHTSA 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 NHTSA's review of potential vehicle safety issues. Respectfully, Vehicle Owner

NHTSA ID

11751053

Incident

May 22, 2026

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

NHTSA ID

11716185

Incident

Jan 28, 2026

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

NHTSA ID

11660309

Incident

May 10, 2025

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.

NHTSA ID

11573361

Incident

Jan 27, 2024

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.

NHTSA ID

11440475

Incident

Oct 25, 2021

Mileage

87,000 mi

SLIDING DOORS ARE PONE WHEN CAR IS UN MONTN, THIS PROBLEM WILL CAUSE A FATAL ACCIDENTS,THE WATER PUMP HAS A DEFECTS.

NHTSA ID

11390084

Incident

Jan 18, 2021

Mileage

50,000 mi

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.

NHTSA ID

11316319

Incident

Oct 9, 2019

Mileage

48,000 mi

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.

NHTSA ID

11302373

Incident

Jan 20, 2020

Mileage

36,650 mi

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). *TR

NHTSA ID

11302322

Incident

Dec 26, 2019

Mileage

57,505 mi

TL* THE CONTACT CALLED ON BEHALF OF THE OWNER OF A 2015 TOYOTA SIENNA. UPON STARTING THE VEHICLE, THE TRACTION INDICATOR ILLUMINATED AND AN ABNORMAL NOISE WAS HEARD COMING FROM THE ENGINE COMPARTMENT. THE VEHICLE WAS TAKEN TO THE PLAZA TOYOTA DEALER (2721 NOSTRAND AVE, BROOKLYN, NY 11210, 347-983-5652) WHERE IT WAS DIAGNOSED WITH AN UNKNOWN WIRING FAILURE DUE TO RODENTS ENTERING THE ENGINE COMPARTMENT. THE VEHICLE OWNER HAD THE VEHICLE REPAIRED, BUT WAS UNAWARE OF THE REPAIR SPECIFICS. THE FAILURE RECURRED THREE MONTHS LATER AND THE VEHICLE WAS TAKEN BACK TO THE SAME DEALER WHERE IT WAS DIAGNOSED THAT THE WIRING WAS DESTROYED AGAIN BY RODENTS. THE VEHICLE WAS NOT REPAIRED AGAIN. THE MANUFACTURER WAS MADE AWARE OF THE FAILURES AND REFERRED THE CONTACT BACK TO THE DEALER. THE FAILURE MILEAGE WAS 16,382.

NHTSA ID

11089088

Incident

Jan 3, 2018

Mileage

16,382 mi

TL* THE CONTACT OWNS A 2015 TOYOTA SIENNA. WHILE STATIONARY, THE VEHICLE CAUGHT FIRE WITHOUT WARNING. THE CONTACT STATED THAT SMOKE CAME FROM THE ENGINE COMPARTMENT AND FLAMES EMERGED DIRECTLY AFTERWARD. A POLICE REPORT WAS FILED. THE FIRE DEPARTMENT EXTINGUISHED THE FIRE. THE CONTACT'S TWO CHILDREN RECEIVED MEDICAL TREATMENT FOR SMOKE INHALATION. THE CONTACT STATED THAT THE VEHICLE HAD AN OPEN RECALL PER NHTSA CAMPAIGN NUMBER: 16V858000 (STRUCTURE). THE MANUFACTURER WAS MADE AWARE OF THE FAILURE. THE FAILURE MILEAGE WAS 42,000.

NHTSA ID

10969725

Incident

Mar 18, 2017

Mileage

42,000 mi

TL* THE CONTACT OWNS A 2015 TOYOTA SIENNA. WHILE DRIVING UP A HILL, SMOKE ENTERED THE VEHICLE AND FLAMES APPEARED UNDER THE HOOD. THE CONTACT WAS ABLE TO EXIT THE VEHICLE. THE FIRE EXTINGUISHED ON ITS OWN, BUT THE VEHICLE WAS DAMAGED EXTENSIVELY. THE VEHICLE WAS TOWED TO A REPAIR SHOP AND A COLLISION CENTER TO REPAIR THE DAMAGES. THE MANUFACTURER TOWED THE VEHICLE TO A DEALER. THE CAUSE OF THE FAILURE WAS NOT DETERMINED. THE VIN AND FAILURE MILEAGE WERE NOT AVAILABLE. UPDATED 03/15/17*LJ *CN

NHTSA ID

10945819

Incident

Apr 27, 2016

TL* THE CONTACT OWNS A 2015 TOYOTA SIENNA. WHILE DRIVING 55 MPH, THE VEHICLE STALLED WITHOUT WARNING. THE CONTACT SMELLED A BURNING ODOR FROM THE VEHICLE AND CALLED A TOW COMPANY TO TOW THE VEHICLE TO HIS RESIDENCE. THE VEHICLE WAS TOWED TO AN AUTHORIZED DEALER WHERE THE CONTACT WAS INFORMED THAT THE ENGINE HAD CAUGHT FIRE. THE ENGINE WAS NOT REPLACED; HOWEVER, REPAIRS WERE MADE TO THE FAULTY ENGINE. THE FAILURE MILEAGE WAS 12,000. THE VIN WAS NOT AVAILABLE.

NHTSA ID

10919045

Incident

Sep 1, 2016

Mileage

12,000 mi

WHEN PULLING INTO A PARKING SPACE, THE CARE REVED AND LUNGED FORWARD, APPROXIMATELY 5 FEET WHILE THE FOOT WAS ON THE BRAKE. HAPPENED TWICE, WHEN TURNING RIGHT INTO PARKING SPACE. CALLED DEALER ABOUT INCIDENT AND THEN TOOK VAN INTO DEALER NEXT DAY. THEY CONTACT TOYOTA (CASE #152470163). TOYOTA INFORMED DEALER THAT THIS WAS NOT THAT UNCOMMON WITH SIENNA VANS. IF SOMEONE HAD BEEN IN FRONT OF THE VEHICLE AT THE TIME OF THE FIRST INCIDENT THEY WOULD HAVE BEEN INJURED. IF I HAD BEEN PARKING IN MY GARAGE I WOULD HAVE DAMAGED THE HOUSE. TOYOTA INDICATE THERE WAS NOT A REPAIR AND THAT ONE WAS NOT NEEDED AND TOLD DEALER TO RELEASE THE VEHICLE TO CUSTOMER (QUOTE). THE DEALER THOUGHT IT WAS THE COMPUTER AND THAT IT REVED THE MOTOR AUTOMATICALLY DUE TO USING AC. WE DO NOT UNDERSTAND WHY A COMPUTER CAN NOT BE PROGRAMMED TO MAKE SURE THIS DOES NOT HAPPEN - WE NO LONGER FEEL SAFE IN THE VEHICLE.

NHTSA ID

10761816

Incident

Sep 3, 2015

Mileage

2,615 mi

THERE ARE MULTIPLE ISSUES WITH THIS VEHICLE THAT CAUSE/HAVE CAUSED SAFETY CONCERNS. DURING NIGHT TIME DRIVING, THE ILLUMINATED CRUISE CONTROL STALK WILL BLINK ON AND OFF INTERMITTENTLY. THIS HAS CAUSED THE DRIVER TO ALMOST REAR-END MULTIPLE CARS AS THE FLICKERING LIGHT TAKES THE DRIVER'S EYES FROM THE ROAD. IT WAS FOUND THAT THERE IS AN INTERMITTENT HIGH RESISTANCE CONNECTION WITH UP TO A 9 VOLT DROP AT TIMES. DESPITE THE STEERING COLUMN BEING SWITCHED OUT AND THE PROBLEM BEING FIXED TEMPORARILY, THE PROBLEM RETURNS. THERE IS SOMETHING IN THIS VEHICLE CAUSING THE WIRING IN THE STEERING COLUMN TO SHORT OUT. NOT ONLY IS THE FLICKERING LIGHT VERY DISTRACTING CAUSING A SAFETY ISSUE WITH A POSSIBLE VEHICULAR ACCIDENT, BUT THE CHANCE OF THE FAULTY WIRING CAUSING A FIRE IS ALSO A SAFETY ISSUE. ANOTHER ISSUE THAT HAS BEEN FOUND WITH THIS VEHICLE INVOLVES THE ENGINE. WHILE SITTING AT A STOP LIGHT, THE VEHICLE'S RPM ALL OF A SUDDEN REVVED UP AND THE ENTIRE ENGINE BEGAN SHAKING. IF THE DRIVER HAD NOT HAD THEIR FOOT ON THE BRAKE AT THE TIME THIS HAPPENED, THIS COULD HAVE CAUSED THE DRIVER TO LOSE CONTROL OF THE VEHICLE, POSING A SAFETY ISSUE. *TR

NHTSA ID

10706552

Incident

Feb 7, 2015

Mileage

9,203 mi