2021 Toyota Redundant Sienna — Known Issues & Recalls

When you brake to a stop at low speeds (like at a stop sign or red light), your car accelerates forward even though you're pressing the brake pedal. This unintended acceleration is dangerous and could cause an accident.

Your brakes occasionally stop working briefly, and your van has accelerated even when you had the brakes engaged. This has happened multiple times since you bought the van new in 2021, though your dealer hasn't been able to reproduce the problem. The issue may involve brake system components or engine control interactions that need diagnostic investigation.

Your brakes unexpectedly lose grip and slip while braking, causing a sudden forward surge as if the brakes have released. This happens without warning and unpredictably, creating a dangerous situation where your car moves forward uncontrolled — potentially hitting pedestrians or other vehicles. Multiple technicians at Toyota dealers and Firestone have inspected the car multiple times but cannot reproduce the problem or find a brake system fault. The issue may require advanced diagnostic testing or inspection of brake fluid, brake lines, or the electronic braking system components.

Your car occasionally accelerates when you press the brake pedal, particularly at slow speeds. This happens randomly and unpredictably, not every time you brake. The dealership hasn't found a solution yet. This could potentially be caused by issues with the brake system, accelerator system, or their interaction, and may require diagnostic testing and possible repairs to the brake components, accelerator pedal, or engine control systems.

When you brake going downhill, your car lurches forward, forcing you to press the brake pedal harder than expected. This unexpected forward motion while braking could make it difficult to maintain control on steep grades.

Your car produces sudden jolts or surges when you apply the brakes, which can feel like the car is accelerating even though you're braking. This may happen because the braking system is switching between regenerative braking (which captures energy) and traditional mechanical braking, and this issue has been reported frequently in 2021 and 2022 Siennas. The fix likely involves a software update or recalibration of the brake system to smooth the transition between these two braking modes.

You purchased a 2021 Toyota Sienna and were not informed at the time of sale that it had an active safety recall (23TA15) affecting the airbags. You only discovered the recall months later when trying to list the vehicle for rental, after already driving it across state lines with your family. Toyota did not provide you with written confirmation of when the recall became active or give you proper warning before you used the vehicle. The recall prevented you from using the vehicle for its intended business purpose while waiting for the repair to be completed.

Your 2021 Toyota Sienna's airbag sensor failed to work properly at around 30,000 miles. Toyota issued a recall (Campaign 23V865000) to fix this, but the replacement part wasn't available when you needed it. The manufacturer told you to stop driving the vehicle but didn't offer any other help or timeline for when the part would arrive. The repair will likely involve replacing the faulty airbag sensor with an updated one from Toyota.

Your airbag system has had an unresolved issue for nearly two years, and no fix has been made available yet. This safety concern is making you feel unsafe driving the vehicle. The repair will likely require a software update or replacement of airbag system components to address the underlying defect.

You were not notified promptly about Safety Recall 23TA15 for your 2021 Toyota Sienna, which involves the airbag system. This delayed notification exposed your family to a safety risk while you were unaware of the problem. The recall may require inspection or replacement of airbag components to ensure they function properly in a crash.

Your 2021 Toyota Sienna was subject to an airbag recall (NHTSA 23V865) over 22 months ago, with a promised repair date more than a year in the past. You're concerned about the status of this recall and why the repair hasn't been completed yet. Getting your airbags inspected and repaired by a Toyota dealer to address the recall issue is needed.

Your air conditioning system stopped working properly, which caused your windows to fog up and reduced visibility — a safety concern. The dealer found that the AC refrigerant lines corroded due to galvanic corrosion where steel brackets contact aluminum line-sets, especially in Michigan's salty winter conditions. The corroded lines developed a leak that let all the refrigerant escape. Fixing this issue requires replacing the entire line-set assembly, though the same corrosion problem could occur again without a design improvement.

Your driver's side door mirror vibrates while driving, making the reflection shaky and hard to see clearly. The passenger mirror works fine with no vibration. While the dealer says this is normal, you've never experienced this issue in 30+ years of driving other vehicles. The fix would likely involve inspecting and tightening the mirror's mounting bracket or replacing the mirror assembly if the mounting hardware is defective.

Your Sienna lost all electrical power and engine power without warning while driving on a busy highway, forcing it to stop abruptly in traffic with your family at risk. A dashboard message indicated "Hybrid System Failure," and the wheels locked so the car had to be towed. A mechanic found a broken transmission shaft, which may have caused the sudden power loss. The repair will likely require transmission replacement or shaft repair.

Your engine suddenly made a loud metal shredding and knocking noise when you started it, and you shut it off immediately. You discovered a hole in the engine block caused by a thrown rod (an internal engine component that broke and punched through the block), even though your oil was in good condition and all maintenance was up to date. The mechanic couldn't identify what caused this sudden failure. The engine will likely need to be rebuilt or replaced.

Your 2021 Toyota Sienna was sold with multiple serious safety defects that were not disclosed. The airbag and seatbelt system showed warning lights caused by improper third-party wiring, indicating potential failures in these critical safety features. The dealer was notified but did not address these issues before sale. Fixing this will require a professional inspection and rewiring of the airbag and restraint system to restore proper function.

Your 2021 Toyota Sienna Hybrid experienced a sudden engine failure while driving—a low oil pressure warning appeared, the engine lost power and went into limp mode, and then a connecting rod broke through the engine block, causing complete engine failure and leaving metal debris in the engine compartment. Before this happened, you noticed rough idling and slight shaking when the engine switched from battery to gas power after sitting, but the van drove normally otherwise despite regular maintenance. The repair will require complete engine replacement or extensive engine block repairs.

Your second-row passenger seat recline mechanism isn't working, leaving the seat stuck in a very reclined position. This could affect how well the side airbag protects a passenger in that seat during a collision, since airbags work best when passengers are sitting upright. The fix will likely involve repairing or replacing the seat recline mechanism.

You purchased a 2021 Toyota Sienna in June 2024 and were told an open safety recall (23TA15) would be fixed soon, but over a year later no repair has been offered. Toyota's own timeline indicates the repair should be available in Washington State, but dealers keep saying no fix exists yet. This leaves you driving a vehicle with unaddressed safety concerns.

Your Sienna is making unusual sounds from the engine or transmission area. Additionally, two rubber seals on your minivan keep warping and failing—Toyota applied tape as a temporary fix, but it came off again. Your back door is misaligned, and the passenger sliding door often won't close properly on the first try, requiring multiple button presses. A permanent repair will likely involve replacing the failed rubber seals, realigning the doors, and diagnosing the source of the engine/transmission noise.