2022 Acura MDX

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.

The contact owns a 2022 Acura MDX. The contact noticed quite a bit of water leaking into the trunk of the vehicle. The contact stated she was able to find a smell of mildew. The manufacturer was notified of the failure. The vehicle was taken to a dealer where a leak coming from the trunk was confirmed. The dealer diagnosed the failure to be caused by defective drain tubes on both sides of the trunk. The vehicle was not repaired. The failure mileage was unknown.

NHTSA ID

11766778

Incident

Sep 24, 2026

The splints that control the SH-AWD have stripped out and I'm being told tge transmission and transfer case need to be replaced. I've had all the services done on-time with the dealership I purchased it from.

NHTSA ID

11766774

Incident

Sep 24, 2026

Engine compartment started emitting smoke and hot air coming out of the vents instead of cold air while driving. Smoke partially obstructed my view. I had to stop on the side and look where smoke is coming from. Smoke is coming from AC compressor inside the engine compartment. Vehicle is less than 5 years old and has 47129 miles on it. Defective AC compressor caused a safety issue.

NHTSA ID

11766382

Incident

Sep 17, 2026

Discovered leaking fluid on 9/12/2026. Scheduled service with local Acura dealer on 9/15/2026 and found that the leak is AFT from unserviceable seal between the transmission and transfer case. The recommended repair from dealer is to replace both transmission and transfer case for $15,000. This is a significant issue for a vehicle that had been well maintained.

NHTSA ID

11764689

Incident

Sep 15, 2026

Heard a loud clunk followed by several small clunks when accelerating. Dealer confirmed the transmission & PTU are damaged and the car is no longer AWD. This issue is becoming more widespread with Acura MDXs and is a very expensive repair. From dealer: “FOUND DRIVESHAFT CAN TURN IN PARK WITHOUT TURNING FRONT WHEELS. THIS INDICATED TRANSMISSION AND PTU SPLINES ARE DAMAGED”

NHTSA ID

11762849

Incident

Sep 4, 2026

The car was being driven as normal and while at a stop light the car shut off and alerted the driver with a transmission error code. The car would not start for about 30 mins after the incident. When we took it to be looked at by the dealership we were told that it was related to code P07E4. The dealership reset the system and the code and returned the car back to me. They stated that if this happened again they would need to replace the transmission. My concern is that this happens again while driving at a higher speed or in an area where it is not safe such as a highway or major intersection or road. It's also concerning that a major component of a vehicle would need replacement at normal mileage which is currently at 111,400 miles.

NHTSA ID

11762003

Incident

Aug 23, 2026

Lost all wheel drive rear wheels not turning front wheel drive only. Out of warranty

NHTSA ID

11761535

Incident

Jul 15, 2026

While driving home on a Sunday afternoon, out of nowhere, a very loud pop sound happened followed by grinding. We were so worried that my husband pulled over thinking we had done major damage to the car somehow. Visual inspection under the car yielded nothing leaving us puzzled. No warning lights came on before, during, or after. We had it taken to the Acura dealership in Fairfield, Ohio. The car was still within warranty at this time, and they found nothing nor could they replicate the sound. My husband explained that it sounded to be transmission related. They chalked it up to a loose tie rod end which they “tightened” to solve all of our problems. We left the dealership and took the car home experiencing no further problems. Fast forward to the winter of that same year we realized that no matter what mode we put the car in we didn’t have AWD. Still no warning lights. The following spring, approximately 20,000 miles after experiencing the first loud pop and grind, we started getting error messages on our user dashboard. “All wheel drive system problem. Only front wheels may be powered. See your dealer”. We immediately scheduled a service appointment with the same Acura dealership. Within minutes of having the car examined on the lift the Acura certified technician found the problem to be the AWD transfer case and additionally the transmission. Stating we would need to replace both. They came back with a quote of approximately $18,000 for a new transmission, transfer case, labor, and all associated materials, for which we declined. Currently seeking help for recall as we do not believe a transmission/ transfer case should fail so quickly under normal driving circumstances.

NHTSA ID

11760987

Incident

May 5, 2024

Tech Line Summary Article - Customers are complaining of a clicking noise from front of vehicle while turning at low speeds. This is a temporary solution to address the issue.

"Service Bulletin - A pop noise can occur from the rear roof area when turning into driveways, bumps, or on an incline due to, in some cases, the panoramic roof frame mounting bolts are unable to maintain the necessary clamp force. This can allow shifting, which may lead to a pop noise."

Tech Line Summary - Customers are complaining of a clicking noise from front of vehicle while turning at low speeds. This is a temporary solution to address the issue.

Service Bulletin - Customers are experiencing screeching, squeaking, rubbing, or scraping from the rear wheel area due to rocks are getting caught between the rear brake disk and splash guard.

Dealer Message - American Honda Motor Co., Inc. (AHM) is searching for certain 2019-2025 RDXs and 2022-2025 MDXs with a client complaint of a pop noise in the rear sunroof area. Clients may describe a single pop noise heard while driving over a bump or turning in and out of driveways. To better understand the cause of this condition, AHM would like to inspect the vehicle prior to you attempting a repair of any kind.

Dealer Message - American Honda Motor Co., Inc. (AHM) is searching for certain 2019-2025 RDXs and 2022-2025 MDXs with a client complaint of a pop noise in the rear sunroof area. Clients may describe a single pop noise heard while driving over a bump or turning in and out of driveways. To better understand the cause of this condition, AHM would like to inspect the vehicle prior to you attempting a repair of any kind.