NHTSA shrugs off Acura's slippery AWD defect claims.
Published Date: 8/6/2026
Notice
Summary
This notice sets forth the reasons for the denial of a petition, DP26-001, submitted by Mr. Christopher Mammarella (the Petitioner) to the Administrator of NHTSA (the "Agency") by a letter dated January 9, 2026, under 49 U.S.C. 30162 and 49 CFR part 552. The Petitioner requests the Agency initiate a safety defect investigation into allegations of a mechanical failure that results in the loss of All Wheel Drive (AWD) in certain Model Year (MY) 2021 to 2023 Acura TLX and MY 2022 to 2023 Acura MDX vehicles (the "Subject Vehicles") equipped with Acura's Super Handling All Wheel Drive (SH-AWD). As a result of the failure, these vehicles permanently lose the ability to transfer drive torque to the rear wheels effectively making them front wheel drive only. NHTSA's Office of Defects Investigation (ODI) has determined that the issues raised in the Petition are not likely to result in a finding that a defect related to motor vehicle safety exists. This determination is based on a technical review by ODI of available information, which included: (1) consumer complaints submitted by the petitioner; (2) consumer complaint information in the agency's databases; and (3) other relevant information in possession of the agency. As a result, further investigation of the issue raised by the Petition is not warranted and the Agency, accordingly, has denied the Petition.
Analyzed Economic Effects
4 provisions identified: 1 benefits, 3 costs, 0 mixed.
NHTSA Denies Defect Investigation
On January 9, 2026 a petition (DP26-001) asked NHTSA to open a safety defect probe for certain MY 2021–2023 Acura TLX and MY 2022–2023 Acura MDX vehicles with SH-AWD. On August 6, 2026 NHTSA denied the petition and will not open a formal defect investigation or order a recall based on the information reviewed.
Potentially Large Repair Costs If Failure Occurs
According to the petitioner, when the splined shafts shear the transaxle and PTU must be replaced together, and the cost of that repair can range from $13,000 to $19,000. NHTSA reviewed consumer complaints and warranty data as part of its decision.
No Driver Warning When AWD Stops Working
The SH-AWD system lacks any direct feedback to show real-time torque transfer, so the vehicle display can indicate power is going to the rear wheels even when the rear is not receiving torque. Operators often remain unaware of the condition until they encounter a low-friction surface or a technician discovers the issue.
Loss of AWD Not Found To Cause Control Loss
NHTSA's Office of Defects Investigation concluded the reported shearing of splined shafts that stops rear torque transfer does not result in a loss of motive power or vehicle control for the subject vehicles. ODI reported it is not aware of any crashes attributed to the loss of SH-AWD in these vehicles.
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