Acura MDX Investigations
NHTSA Office of Defects Investigation records
No Restart After Auto Start/Stop Engages
On June 3, 2022, the Oï¬ce of Defects Investigation (ODI) opened Preliminary Evaluation PE22005 after the agency received VOQs and several ï¬eld 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 traï¬c 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 (âPGM-FIâ) 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
Engine failure
The Office of Defects Investigation (ODI) has received 414 reports of connecting rod bearing failures in the 3.5L V6 engine used in the following vehicles: Model Years (MY) 2018-2020 Acura TLX, MY2016-2020 Acura MDX, MY2016-2020 Honda Pilot, MY2018-2020 Honda Odyssey, and MY2017-2019 Honda Ridgeline. The subject engine failures were analyzed as part of a Recall Query (RQ24013). It was determined that these engine failures are outside the scope of Honda Recall 23V-751. Further, evidence gathered in conjunction with RQ24013 does not suggest this failure is caused by the same crankshaft manufacturing defect that is addressed by Honda in Recall 23V-751. Based on analysis of data from RQ24013, NHTSA has closed that investigation. The significant number of reports of engine failure in vehicles outside the scope of RQ24013 presents a potential safety risk that warrants further investigation. ODI is opening this Preliminary Evaluation (PE) to further evaluate the scope and severity of the potential problem and to fully assess the potential safety-related issues. To review the ODI reports cited in the Opening Resume ODI Report Identification Number document, go to NHTSA.gov.
Engine failure
On November 8, 2024, the Office of Defects Investigation (ODI) opened Recall Query RQ24013 to assess the scope of Honda recall 23V-751 after receiving complaints that alleged connecting rod bearing failures in vehicles that were not within the scope of recall 23V-751. In November 2023, Honda recalled 248,999 various Model Year (MY)2016â2020 Honda and Acura vehicles equipped with the 3.5L V6 engine. Honda recalled these vehicles due to a crankshaft manufacturing defect that caused premature connecting rod bearing wear and engine seizure. While the out-of-scope failures involved in these complaints appear to have a very similar failure mechanism as the recalled engines, a thorough analysis of all available data from Honda has not indicated that the same manufacturing defect exists in the out-of-scope engines as the engines recalled by 23V-751. Based on this analysis ODI has determined that Honda has properly defined the scope of recall 23V-751. Consequently, ODI will close this RQ investigation. NHTSA will continue to investigate these complaints of engine failure as part of a new Preliminary Evaluation Investigation (PE25008). The Agency reserves the right to take additional act
All wheel drive allegation
The Office of Defects Investigation (ODI) received 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 contends that the interfacing splines between the transmission and the rear wheel drive power take off unit are failing. 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 results in a reduction of vehicle directional control. The Petitioner cites 48 complaints received by ODI alleging the same failure. ODI will evaluate these complaints to determine if they are related to the failure cited in the Petition and will conduct a technical review under 49 CFR Part 552. This Defect Petition is being opened to evaluate whether to grant or deny the Petition. The Petition can be viewed at NHTSA.gov under NHTSA Number 11712885. The VOQ numbers referenced in the Petition are listed below. 11615217, 11619288, 11633510, 11634618, 11634979, 11636677, 11637484, 11638577, 11638902, 11640757, 11642028, 11642839, 11644661, 1
About NHTSA Investigations
NHTSA investigations include Preliminary Evaluations (PE), Engineering Analyses (EA), Defect Petitions (DP), and Audit Queries (AQ). Investigations may lead to recalls if defects are confirmed. An open investigation means NHTSA is actively examining the issue.