What 36 owners told NHTSA about the 2021 Toyota Sienna

FAILURE: Brake control system. Vehicle intermittently surges forward while braking at low speed, most often through a curve — the brakes momentarily release and the vehicle lurches before braking resumes. Appears to occur during the transition between regenerative and friction braking. Vehicle available for inspection. SAFETY RISK: Unpredictable momentary loss of braking at low speed, in parking lots, residential streets and curves where pedestrians and other vehicles are close. Driver cannot anticipate it. WARNING LAMPS: None. No lamp, no message, no stored trouble code. Present since early in ownership; purchased new September 2021. CONFIRMED BY DEALER: No. Reported to a Toyota dealer in 2022 under warranty. Dealer test drove, could not reproduce the intermittent condition, took no action. Also reported in writing to Toyota in August 2022; no substantive response. MANUFACTURER REMEDY: In May 2024 Toyota issued TSB T-SB-0047-24, a brake control module software update for this exact low-speed braking condition on 2021-2022 Sienna Hybrids. Warranty had lapsed, so it was applied at owner expense in late June 2026 at ~156,000 miles. The defect persists after Toyota's own remedy. The surge still occurs, including within the past week at ~157,000 miles. REQUEST: A TSB is not a recall — owners are not notified, and the software remedy did not eliminate the defect on this vehicle. Request that ODI evaluate whether this condition warrants a defect investigation and recall.

NHTSA ODI 11750094

FAILURE: Blind spot monitor module failed due to a corroded internal electrical connector. The failure disabled both the Blind Spot Monitor (BSM) and Rear Cross-Traffic Alert (RCTA). Both remain inoperative. The failed component has not been replaced and is available for inspection. SAFETY RISK: Two active safety systems are disabled. The vehicle no longer warns of vehicles in the blind spot during lane changes, and no longer warns of cross traffic when backing out of parking spaces or driveways. WARNING LAMPS: Yes. Multiple warning lamps illuminated simultaneously in February 2026, including BSM and RCTA malfunction messages. No prior symptoms or gradual degradation. CONFIRMED BY DEALER: Yes. A Toyota dealer diagnosed the corroded connector as the cause. Repair quoted at approximately $2,500-$3,000. Repair not performed. INSPECTED BY MANUFACTURER: Diagnosed by a Toyota dealer. Goodwill assistance was requested from Toyota and declined, on the stated grounds that the vehicle had not been regularly serviced at a Toyota dealer. NOT A WEAR ITEM: A sealed electrical connector that corrodes to failure is a component defect. No step in the manufacturer's published maintenance schedule inspects, services, or protects this connector — no owner action could have prevented it, and service history has no bearing on a connector that no service procedure touches. Vehicle purchased new September 2021; failure occurred at approximately [XXX] of age. REQUEST: Request that ODI evaluate whether the BSM sensor and connector design used on this vehicle is inadequately sealed against moisture intrusion, resulting in premature failure of two active safety systems. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11750096

Car surged as brakes were applied when stopping. Very dangerous. Could have easily rear-ended another vehicle. Surge was immediate and occurred when brake was being applied. Not confirmed yet, but another driver of vehicle told me of having similar problems when braking this car. Very scary. No warnings or messsages.

NHTSA ODI 11747761

Unexpected failure of the acceleration pedal to accelerate from a complete stop to a go at an intersection. The electric vehicle (EV) motor began accelerating up to about 3 mph than instantly had a failure to accelerate, even with the gas pedal continuously pushed to the floor. After about 4 to 5 seconds the engine kicked on and began accelerating. The failure seemed to occur during the EV motor swapping over to the gas powered engine. This has been the fourth occurrence and can be extremely dangerous at intersections with oncoming traffic. No fault codes or check engine lights came on.

NHTSA ODI 11746943

1. The rear underbody air conditioning (AC) lines and their supporting structural mounting brackets have failed due to severe corrosion. Specifically, a heavy steel mounting bracket has rusted excessively, causing localized galvanic corrosion at the point of contact with the adjacent aluminum AC lines. This structural and material failure caused the aluminum line to erode, crack, and leak high-pressure chemical refrigerant into the environment. The vehicle, failed components, and detailed photographic evidence of the galvanic corrosion and rusted bracket are fully available for inspection upon request. 2. The failure presents multiple safety and health hazards: •Environmental and Inhalation Hazard: The high-pressure leak of mobile air conditioning refrigerant (R-1234yf or R-134a) releases a hazardous chemical compound directly beneath the cabin. •Defrost and Visibility Failure: The rapid loss of system pressure completely disables the vehicle’s climate control and window defrosting/demisting capabilities, severely compromising driver visibility during inclement or humid weather. •Structural Degradation: The severe rust and erosion of the underbody mounting bracket mean structural components are failing prematurely on a 2021 model, creating a risk of loose or dragging underbody debris at highway speeds. 3. The physical failure (loss of refrigerant and severe physical corrosion) has been visually confirmed. However, the Toyota dealership service center actively refused to document the cause. However, photographic evidence clearly reveals the distinct, localized galvanic corrosion occurring exactly where the rusted steel bracket contacts the aluminum line. Further, Toyota’s highlander model had this same problem which was addressed through T-SB-0021-26. 4. The vehicle was inspected by an authorized Toyota dealership which acknowledged the leak but refused to provide a written technical breakdown. 5. Rust, corrosion, and loss of cooling ability.

NHTSA ODI 11745261

My 2021 Toyota Sienna Hybrid has an intermittent and dangerous brake failure where the brakes suddenly release pressure during normal braking. When slowing down—especially at lower speeds or approaching a stop—the brake pedal briefly loses resistance and the vehicle surges forward as if the brakes let go. I must immediately re‑apply hard pedal pressure to avoid rolling into traffic or another vehicle. The vehicle as a result can stop up to six feet past the intended stopping point in some instances. This issue is unpredictable and has occurred multiple times. It creates a serious safety risk. Toyota performed T‑SB‑0047‑24 (Brake ECU Reprogramming) on my vehicle, whereafter the brakes seemed to function normally for several months, but the problem resurfaced and occurred threee time in one week in May of 2026, which prompted me to bring it backk to Toyota for another look. The dealer has been unable to reproduce the issue and therefore has not repaired it. The veicle has been returned to me, and continues to have the problem intermittently at a random frequency. Toyota corporate Brand Engagement Center has been notified, and a case was opened (Ref # 260528002416). This case was closed however after telling me that the dealership connot reproduce the problem, therefore they cannot repair it. This appears to be a brake control defect involving the hybrid brake‑by‑wire system. Because the failure is intermittent and leaves no diagnostic codes, it is extremely difficult for the dealer to diagnose, but the safety risk is severe. I'd like to advise that I have owned and driven earlier hybrid models (2012-14) that never exhibited this type of brake failure. I'd also like to point out... an internet search of this problem reveals that this problem seems to be prevelant in newer Toyota hybrid models. This was confirmed by the service manager at my local dealership. I have not been informed of any continuing engineering efforts given the failure of the TSB.

NHTSA ODI 11741894

SRS light has been showing up on the dashboard, off and on for 3 weeks. Diagnostic reader completed by the dealership states it is an airbag module malfunction of the 2nd row left passenger seat. The seat has never been removed, there have been zero accidents and no damage to the seat or wiring.

NHTSA ODI 11740978

Both front struts of the vehicle have failed and are leaking. There is only 36,000 miles on this vehicle when they should last 200,000 miles per Toyota's service department. Toyota refuses to acknowledge this is their problem and that it's a "wear and tear' part. However clearly these parts should not fail after so little usage.

NHTSA ODI 11739075

Unknown, I got the SRS Airbag system malfunction in my vehicle, I got the same error in my vehicle dashboard a few times in the past but it would go away and since yesterday I have the message in my dashboard

NHTSA ODI 11737555

We were stopped at a stoplight. As soon as we stepped on the gas pedal, there was a loud clunk sound and plastic parts started flying out from under the car. We immediately pulled over. Oil was spilling out everywhere. The transmission oil pump was laying on the inside of the engine compartment. We had towed to Toyota. They diagnosed a bent piston went through engine which also caused a hole in the transmission. I had it towed for a 2nd opinion. Neither toyota or the 2nd opinion had ever seen anything like it. My mechanic also said there are a bunch of other suspension parts that were damaged due to the violent stop of the engine. There are a few of the same incidents online in chat rooms. The car is totalled and we are out of a car now.

NHTSA ODI 11730547

The contact owned a 2021 Toyota Sienna Hybrid. The vehicle was parked in the driveway when an explosion occurred; the vehicle burned down. The contact was inside the residence when a loud noise was heard, and the house "rocked." The contact ran to the front of the house to investigate and noticed that the vehicle was engulfed in flames. The fire damaged the driveway, melted the garage door, and melted a landscaping retaining wall. The fire damaged the post on the front porch. The contact and her family were unable to exit through the front door due to the fire and used the sliding kitchen door to exit the residence. The fire department was called to the scene. Per the contact, three fire trucks were at the scene. The fire department informed the contact that the fire went up to 3,000 degrees. The fire department concluded that the fire started from underneath the driver's back panel. The contact stated that the gas tank was underneath that area and believed the gas tank may have contributed to the fire. The towing company towed the vehicle to a towing yard, and it was later picked up and towed to an unknown location. The insurance company was notified and declared the vehicle a total loss. The manufacturer was made aware of the failure and advised the contact that an inspection was needed on the vehicle and asked for the location of the vehicle.  However, the contact was awaiting the results. The failure mileage was approximately 80,000.

NHTSA ODI 11729036

The car jerks when coming to a stop. Like when the regenerative system is disengaged it jerks. For the Adaptive cruise control the car will accelerate instead of braking when another car merges in front of you.

NHTSA ODI 11717402

The contact owns a 2021 Toyota Sienna Hybrid. The contact received notification of NHTSA Campaign Number: 23V865000 (Air Bags). Upon contacting the local dealer, the contact was informed that the parts for the recall repair were on backorder. The contact had not experienced a failure related to the recall. The manufacturer had not been contacted. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair.

NHTSA ODI 11678695

The contact owns a 2021 Toyota Sienna Hybrid. The contact received notification of NHTSA Campaign Number: 23V865000 (AIR BAGS); however, the part to do the recall repair was not yet available. The contact stated that the SRS warning light was illuminated. The local dealer was contacted. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was not made aware of the issue. The failure mileage was unknown. VIN tool confirms parts not available.

NHTSA ODI 11675432

The contact owns a 2021 Toyota Sienna Hybrid. The contact stated that while the vehicle was parked, the contact observed a melted spot, almost identical on the driver’s and front passenger’s lower back rest on the seats. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure. The failure mileage was approximately 60,000.

NHTSA ODI 11652064

The contact owns a 2021 Toyota Sienna Hybrid. The contact stated that while driving at an undisclosed speed, there was an abnormal rattling sound coming from the second-row seats. The message to "Check Rear Seats" was displayed. No warning lights were illuminated. The vehicle was not taken to the dealer or an independent mechanic. The vehicle was not repaired. After investigating the failure, the contact related the failure to NHTSA Campaign Number: 25V086000 (Seats); the VIN was included, and the vehicle was repaired. However, the contact was informed that the remedy was for the third-row seat only. The manufacturer was notified of the failure, a case was opened, and the contact was referred to the NHTSA Hotline to report the failure. The failure mileage was 169,000.

NHTSA ODI 11647745

The contact owns a 2021 Toyota Sienna Hybrid. The contact received notification of NHTSA Campaign Number: 23V865000 (Air Bags); however, the part to do the recall repair was unavailable. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was not made aware of the issue. The contact had not experienced a failure. VIN tool confirms parts not available.

NHTSA ODI 11644161

The contact owns a 2021 Toyota Sienna Hybrid. The contact was notified of NHTSA Campaign Number: 23V865000 (Air Bags); however, the part to do the recall repair was not yet available. The local dealer was made aware of the issue and confirmed that parts were not yet available. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was made aware of the issue. The contact had not experienced a failure. VIN tool confirms parts not available.

NHTSA ODI 11640336

The contact owns a 2021 Toyota Sienna Hybrid. The contact received notification of NHTSA Campaign Number: 23V865000 (AIR BAGS); however, the part to do the recall repair was unavailable. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was made aware of the issue. The contact had not experienced a failure. VIN tool confirms parts not available.

NHTSA ODI 11628808

The contact owns a 2021 Toyota Sienna Hybrid. The contact received notification of NHTSA Campaign Number: 23V865000 (Air Bags); however, the part to do the recall repair was unavailable. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was made aware of the issue. The contact had not experienced a failure. VIN tool confirms parts not available.

NHTSA ODI 11617694

The contact owns a 2021 Toyota Sienna Hybrid. The contact received notification of NHTSA Campaign Number: 23V865000 (Air Bags); however, the part to do the recall repair was not yet available. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The dealer was made aware of the issue and confirmed that parts were not yet available. The manufacturer was made aware of the issue and confirmed that parts were not yet available. The contact had not experienced a failure. VIN tool confirms parts not available.

NHTSA ODI 11604502

The contact owns a 2021 Toyota Sienna Hybrid. The contact received notification of NHTSA Campaign Number: 23V865000 (Air Bags) however, the part to do the recall repair was not yet available. The local dealer was contacted. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was not made aware of the issue. The contact had not experienced a failure. VIN tool confirms parts not available.

NHTSA ODI 11603012

The contact owns a 2021 Toyota Sienna Hybrid. The contact stated that the vehicle was experiencing inaccurate fuel gauge readings. The contact stated while starting the vehicle, the fuel gauge reading displayed that the fuel tank was empty; however, while the contact was attempting to refuel the vehicle at the gas station, she became aware that the fuel tank was not empty and that there was sufficient fuel in the vehicle. The vehicle was taken to the CarMax dealer, where it was driven and refueled several times; however, the failure could not be replicated. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline for assistance. The failure mileage was approximately 50,300.

NHTSA ODI 11596197

The contact owns a 2021 Toyota Sienna Hybrid. The contact received notification of NHTSA Campaign Number: 23V865000 (Air Bags) however, the part to do the recall repair was not yet available. The local dealer was not contacted. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was not made aware of the issue. The contact had not experienced a failure. VIN tool confirms parts not available.

NHTSA ODI 11596277

The contact owns a 2021 Toyota Sienna Hybrid. The contact stated that while driving at an undisclosed speed, the contact heard an abnormal splashing sound inside the vehicle. The contact stated that while the vehicle was parked, there was water coming from underneath the doors. The vehicle was not diagnosed or repaired by an independent mechanic or the dealer. The contact related the failure to Technical Service Bulletin: 0121-20 (Sloshing or Splashing Noise Caused by Water Inside Doors); however, the vehicle was not covered under the TSB. The manufacturer was made aware of the failure but provided no assistance. The failure mileage was approximately 22,500.

NHTSA ODI 11592878