2020 Acura MDX

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.

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.

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)2016–2020 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 action if warranted by new circumstances.

The contact owns a 2020 Acura MDX. The contact stated that while driving at various speeds, the vehicle hesitated while accelerating. The contact stated that later, while parking the vehicle, the vehicle unintended accelerated and drove over a curb and crashed into a tree. The vehicle crashed into the tree, and the front wheels continued spinning without the accelerator pedal being depressed, and the engine was turned off. During the crash, the front end was severely damaged, but the air bags failed to deploy. The vehicle was driven to the residence and examined by an independent mechanic, and it was determined that the PCM had malfunctioned and there was a computer miscommunication between the engine and the transmission. The vehicle was later towed to the local dealer. The failure mileage was 45,000.

NHTSA ID

11764060

Incident

Sep 11, 2026

Mileage

45,000 mi

LKAS, forward collision, high beam all alerts are going off and have been told it's a camera system that gets over heated. This is not a easy fix and needs to be recalled to clear up the codes and alerts.

NHTSA ID

11763916

Incident

Sep 12, 2026

The contact owns a 2020 Acura MDX. The contact stated that while idling and driving on several occasions at various speeds, there was an abnormal knocking sound coming from the engine compartment. The vehicle was taken to an independent mechanic to be diagnosed. The mechanic determined that there was internal engine rod bearing failure, and that the engine needed to be replaced. The contact believed that the failure was associated with Manufacturer Recall Number: 24-001. The manufacturer was notified of the failure. The failure mileage was 65,128.

NHTSA ID

11763569

Incident

Sep 4, 2026

Mileage

65,128 mi

The contact owns a 2020 Acura MDX. The contact stated that while operating the vehicle, the oil light illuminated. The contact stated that after restarting the vehicle, while driving, the vehicle failed to properly accelerate, with a ticking and knocking sound coming from the engine compartment. The vehicle was later towed to the local dealer to be diagnosed and metal shavings from the engine bearings were found in the engine oil. The contact was informed that the engine needed to be replaced. The vehicle was not yet repaired. The manufacturer was notified of the failure, but no assistance was offered. The contact was informed that the VIN was not included in NHTSA Campaign Number: 23V751000 (ENGINE AND ENGINE COOLING). The contact stated that the vehicle had experienced the failure listed in the recall. The failure mileage was 85,000.

NHTSA ID

11763037

Incident

Sep 3, 2026

Mileage

85,000 mi

Engine seized multiple times. Completely broken now. Online it says many people have these problems.

NHTSA ID

11762319

Incident

Sep 4, 2026

My 2020 Acura MDX has experienced repeated Auto Idle Stop system malfunctions. When the system activates at a stop, the engine shuts off and does not return to normal operation as expected. The incidents are becoming more frequent and create a safety concern when the vehicle is stopped in traffic. This problem has been reported by telephone on multiple prior occasions. The 12-volt battery has also been replaced multiple times because we believed the battery was causing the problem, but the condition has continued.

NHTSA ID

11762152

Incident

Sep 4, 2026

Multiple errors Lane departure and advanced driver support, ACC LKAS, auto high beam, and braking system. Looking into this more i see lots of people with the same issue failing front facing camera and not a cheap fix. Is there any current investigations into this problem or a software upgrade? I clear the errors and they come back once car is turned off and back on. If no fix to the current system there should be a way to disable LKAS and ACC without spending $2000 to replace the system.

NHTSA ID

11759085

Incident

Jul 22, 2026

The contact owns a 2020 Acura MDX. The contact stated that while driving approximately 35 MPH, there was an abnormal knocking sound coming from the vehicle before the vehicle stalled. The vehicle failed to restart. The maintenance warning light was illuminated. The contact stated that the failure was associated with NHTSA Campaign Number: 23V751000 (Engine and Engine Cooling). The vehicle was towed to the residence. The local dealer was contacted to schedule an appointment, but the vehicle had not been diagnosed or repaired. The manufacturer was not contacted. The approximate failure mileage was 60,541.

NHTSA ID

11757385

Incident

Aug 15, 2026

Mileage

60,541 mi

Owner Notification Letter - Under certain circumstances, after coming to a stop and the idle stop feature engaging, the vehicle may not automatically restart. Acura is providing a product update with a new PGM-FI software update to fix this issue.

Dealer Message - Under certain circumstances, after coming to a stop and the idle stop feature engages, the vehicle may not automatically restart. Typically, the client can immediately restart the vehicle by selecting Park and pushing the ENGINE START/STOP button.

Service Bulletin - Under certain circumstances, after coming to a stop and engaging idle stop the vehicle may not restart automatically due to excessive cylinder pressure and/or low cranking torque. Typically, the client can immediately restart the vehicle by selecting Park and pressing the ENGINE START/STOP button.

Service Bulletin - The AWD warning light is on with one or more AWD DTCs having been set due to water intrusion into the electric oil pump motor connector area corrodes the terminals.

Service Bulletin - The AWD warning light is on potentially due to water intrusion into the rear differential pump motor connector area that corrodes the terminals.

Service Bulletin - Client complaint of A/C not blowing cold air due to oil/refrigerant leak from the A/C compressor shaft seal.