2021 Acura TLX

On June 3, 2022, the Office of Defects Investigation (ODI) opened Preliminary Evaluation PE22005 after the agency received VOQs and several field reports concerning the Auto Idle Stop (AIS) feature on 2016-2019MY Honda Pilot vehicles. The complaints allege that the engine fails to restart on its own from a complete stop at a traffic light or road intersection with the AIS function engaged. The subject vehicles are equipped with a 3.5L engine with a 9-speed automatic transmission. On January 6, 2023, Honda released service bulletins 23-008 and 23-009. These service bulletins address the failure to restart issue in the 2016-2019MY Honda Pilot vehicles, as well as the 2015-2020 Acura TLX, 2016-2020 Acura MDX, 2019-2022 Honda Passport, and 2020-2023 Honda Ridgeline vehicles. The repair outlined in the service bulletins is a two-stage countermeasure to remedy the issue. The first stage is a Programmed Fuel Injection (“PGM-FI”) software update. The second stage is only deployed if the software update fails to remedy the issue. The second stage, depending on the model and model year, consists of replacement of the starter assembly, starter relays, and a valve adjustment. Additionally, Honda extended the warranty coverage to 10 years with unlimited mileage for vehicles requiring the second stage component replacement. ODI continues to receive complaints of the AIS failure to restart, with many complainants alleging the campaign countermeasures had been completed.NHTSA has reviewed Honda's Information Request Letter responses involving warranty claims, lawsuits, and consumer complaints in addition to ODI's own data. This Engineering Analysis is being opened to further consider the potential safety defect, including gathering additional data regarding Honda’s service campaign efficacy. ODI is additionally expanding the scope to encompass all vehicles addressed in Honda’s service bulletins 23-008 and 23-009 as well as newer model year vehicles, which are substantially similar to the vehicles covered by the service campaign. To review the ODI reports cited in the Opening Resume ODI Report Identification Number document, go to NHTSA.gov.

The Office of Defects Investigation (ODI) has completed its review of a Petition dated January 9, 2026, requesting an investigation into the loss of the optional all-wheel drive capability in model year (MY) 2021-2023 Acura TLX and MY 2022-2023 Acura MDX vehicles. The Petition alleges failures in the interfacing splines between the front wheel drive transaxle and the rear wheel drive power take off unit. Failure of these splines prevents the transfer of drive power to the rear axle, making the vehicle front wheel drive only. The Petition further alleges that this failure reduces vehicle directional control. Most traditional AWD systems utilize mechanical and passive measures. These systems have the tendency to distribute torque along the path of least resistance, such as a wheel that has lost contact with the ground or is on a low friction surface such as ice. To compensate for this, many manufacturers use the brake system to redirect torque to the wheels with more traction.  However, in this style of AWD system, a failed drive shaft or similar disconnection prior to the brakes often results in drive power being lost to the disconnected component. The consequence of this loss is the inability to maintain speed with surrounding traffic which increases the risks of collisions and injuries to the vehicle occupants. The Subject Vehicles are built upon a platform that was designed primarily as Front Wheel Drive (FWD). The SH-AWD system functions more as a performance enhancement feature rather than a stability feature. Even if the SH-AWD is nonoperational, the vehicles retain full mobility via FWD. In addition, the Vehicle Stability Assist (VSA) remains functional, ensuring directional stability through traditional engine and brake-based traction control. Although the condition raised by the Petitioner may degrade the vehicle’s performance characteristics, there is insufficient information to indicate a potential unreasonable safety risk. ODI reviewed 62 Vehicle Owner Questionnaires (VOQs) and several EWR Field Reports alleging the loss of SH-AWD and its impact on the driving dynamics of the subject vehicles. During its analysis, ODI determined that the failure is localized to the mechanical interface between the FWD transaxle and the PTU. Specifically, the failure is the shearing or stripping of the interfacing splined shafts between the FWD transaxle and the PTU, resulting in a permanent loss of torque transfer to the rear of the vehicle. Upon reviewing the technical details of SH-AWD, ODI has found that this failure does not result in any loss of motive power or lead to a loss of vehicle control. Several complaints indicated that the operators were unaware of the mechanical fault until encountering a low friction surface or the condition was identified by a technician during routine maintenance. The SH-AWD system lacks any form of direct feedback for monitoring real time torque transfer to the rear wheels. Therefore, the system will continue to display information indicating power is being supplied to the rear wheels even when power is actually only supplied to the front wheels. ODI’s review did not identify sufficient evidence to indicate that the misinformation has presented a safety issue in the field. ODI did not identify any reports of loss of motive power or vehicle control that could be attributed to the loss of SH-AWD. ODI is not aware of any crashes involving the Subject Vehicles that resulted from the loss of SH-AWD. After thoroughly assessing the material submitted by the Petitioner, consumer complaint information in NHTSA’s databases, and other relevant information already in possession of the Agency, NHTSA has not found sufficient evidence to indicate that the loss of AWD as alleged by the Petitioner is likely to present a safety related defect that would warrant a formal investigation. After full consideration of the available information, and in view of NHTSA’s enforcement priorities, the Petition is denied.  A denial report will be posted in the Federal Register.  The closing of the petition does not constitute a finding by NHTSA that a safety related defect does not exist, and the agency reserves the right to take additional action if warranted by future circumstances.  The Petition can be viewed at NHTSA.gov under ODI Number 11712885.

I am submitting this complaint regarding a transmission failure involving my 2021 Acura TLX, which I believe presents a significant motor vehicle safety defect. The transmission experienced a premature and unexpected failure that resulted in a substantial reduction in vehicle performance, including a loss of power delivered to the rear wheels and a corresponding reduction in vehicle directional control. At the time of the failure, the vehicle's handling characteristics changed unexpectedly, creating a potentially hazardous operating condition. The loss of rear-wheel power adversely affected the vehicle's stability and responsiveness, particularly during acceleration, lane changes, and other driving maneuvers where predictable vehicle control is necessary for safe operation. This condition significantly increased the risk of a crash and exposed both the vehicle occupants and the motoring public to an unreasonable safety hazard. Upon researching this issue, I discovered that transmission failures and related drivetrain defects have been reported by other owners of 2021 Acura TLX vehicles. The existence of multiple similar complaints suggests that this may not be an isolated incident but rather a recurring defect affecting this vehicle model and year. The failure occurred despite the vehicle being maintained in accordance with manufacturer recommendations and without any misuse or modification that would reasonably contribute to such a catastrophic drivetrain failure. A transmission component that affects vehicle propulsion and directional control should not fail under normal operating conditions. Given the nature of the defect and its direct impact on vehicle safety, I respectfully request that the National Highway Traffic Safety Administration investigate this issue to determine whether a broader safety-related defect exists within the 2021 Acura TLX population. If such a defect is confirmed, Acura/Honda should be required to provide an appropriate remedy.

NHTSA ID

11776228

Incident

Nov 3, 2026

While driving over a bump in the roadway, there was a squeaky metallic sound coming from the front passenger’s side suspension. The cause of the failure was not yet determined, and the vehicle was not yet repaired. The local dealer was notified of the failure and advised the to have the vehicle diagnosed. The vehicle was diagnosed and the dealer was unsure what the issue was, and advised to wait until it worsens. The failure mileage was 91,000.

NHTSA ID

11776193

Incident

Oct 22, 2026

My car shakes and rocks like a boat over every bump and when i make turns the car dips really bad and bounces around. It’s been doing this since i got the car and purchase a warranty i could not use from sports Mazda. Its unsafe at high speeds and jerks when switching lanes. I continuously do the alignment every 2-4 weeks. And the toe gets adjusted and it goes right back to the issue. Acura told me this is how their cars drive and it feels unsafe to drive

NHTSA ID

11774579

Incident

Aug 30, 2025

On October 4, 2026, at approximately 6:55 PM, the 2021 Acura TLX suffered a catastrophic and sequential collapse of its primary safety and electronic control systems while in motion. Without warning, the vehicle's dashboard suddenly illuminated with a cascade of severe system malfunctions, beginning with a critical "Brake System Problem" warning, immediately followed by a "Power Steering System Problem," which caused the steering wheel to become dangerously heavy and difficult to maneuver. Simultaneously, a string of secondary critical alerts flashed across the information display, including a "Lane Assist System Problem," effectively disabling the vehicle's automated driver-assist, traction, and stability networks. This total electronic network blackout culminated moments later in a severe collision that caused significant structural damage, including a snapped front axle. Despite the force of the impact meeting the necessary physical criteria for severe crash deceleration, the vehicle’s Supplemental Restraint System (SRS) completely failed, and none of the airbags deployed

NHTSA ID

11772571

Incident

Oct 4, 2026

VEHICLE LOSING TRACTION WHILE DRIVING. CONFIRMED BY [XXX]'S ACURA IN [XXX]. CONFIRMED: TRANSFER CASE WITH BAD TRANSMISSION. VEHICLE NOW INOPERABLE. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11771884

Incident

Sep 8, 2026

I am submitting this complaint regarding a major drivetrain failure in my 2021 Acura TLX Type S SH-AWD with approximately 86,643 miles. My vehicle experienced a complete loss of AWD. The front two wheels are receiving power, but the rear wheels are no longer receiving power. An independent mechanic initially diagnosed a transfer-case/drivetrain failure and advised that the transmission may also be involved. I then took the vehicle to OH Acura of Temecula, where the Acura dealership independently diagnosed the vehicle with transmission and transfer-case failure. The service manager confirmed that my independent mechanic’s diagnosis was accurate. The dealership provided a repair estimate of approximately $16,000. I am concerned because NHTSA previously opened investigation DP26-001 regarding reported failures involving the transmission and transfer case in 2021–2023 Acura TLX SH-AWD vehicles. My vehicle is now experiencing a complete loss of AWD consistent with the issue described in that investigation. I also experienced an unusual grinding noise on September 21, 2026, which lasted approximately five minutes before stopping. I was subsequently told the noise was caused by worn spindles. The noise has not returned, and I am not claiming that issue was related to the drivetrain failure. Acura declined goodwill assistance, citing lack of documentation for transmission maintenance. The vehicle is outside its original warranty. I am submitting this complaint so NHTSA has a record of my vehicle’s actual failure and complete loss of AWD and can consider it alongside other reports involving this vehicle and drivetrain configuration. I can provide the VIN, dealership diagnosis, repair estimate, and supporting documentation if requested.

NHTSA ID

11768412

Incident

Oct 1, 2026

My 2021 Acura TLX has a fuel leak. This is a known issue and manufacture design flaw. The Acura dealership has quoted my $4200 - $4500 to replace the fuel tank. I've contacted Honda and they've only offer $300 "goodwill" credit towards the repair. This is a know issue, a fire hazard, and other 2021 TLX has been recalled for this fuel tank/fuel leak issue via recall.

NHTSA ID

11766764

Incident

Aug 29, 2026

I drive a 2021 Acura TLX TYPE S around 85K miles. I heard a loud clank when I was driving one day, and I loss traction. When I was accelerating I was losing traction and it seem like I lost power while I was moving as well. It seems like I'm driving front wheel drive. I let me foot of the gas and it seems like it's back to normal SH-AWD. I hope this gets looked into and fixed soon.

NHTSA ID

11763748

Incident

Sep 10, 2026

Over The Air Update - Vehicles equipped with the System Updates application are capable of downloading and installing Over the Air System Updates. System Updates contain upgrades that fix a variety of operational errors and/or enhancements that add new functionality. Information for the various software releases can be found in this document. Software version: D.1.6.4

Service Bulletin - Oil leak at the cam chain tensioner inspection cover due to and insufficient sealant adhesion on the inspection cover.

Dealer Message - American Honda Motor Co., Inc. (AHM) is searching for certain 2022- 2024 MDXs & 2021-2025 TLXs with a client complaint of a loose or detached rearview mirror bracket. To better understand the cause of this condition, AHM would like to collect specific parts from the vehicle prior to you attempting a repair of any kind.

Dealer Message - American Honda Motor Co., Inc. (AHM) is searching for certain 2021-2023 TLX ADV’s and 2021-2025 TLX Type S’s with a client complaint of the “Adaptive Damper System Problem” (ADS) error message on the MID (Multi Information Display). To better understand the cause of this condition, AHM would like to collect specific parts from the vehicle prior to you attempting a repair of any kind.

Dealer Message - American Honda Motor Co., Inc. (AHM) is searching for certain 2021-2023 TLX ADV’s and 2021-2025 TLX Type S’s with a client complaint of the “Adaptive Damper System Problem” (ADS) error message on the MID (Multi Information Display). To better understand the cause of this condition, AHM would like to collect specific parts from the vehicle prior to you attempting a repair of any kind.

Dealer Message - American Honda Motor Co., Inc. (AHM) is searching for certain 2021-2023 TLX ADV’s and 2021-2025 TLX Type S’s with a client complaint of the “Adaptive Damper System Problem” (ADS) error message on the MID (Multi Information Display). To better understand the cause of this condition, AHM would like to collect specific parts from the vehicle prior to you attempting a repair of any kind.