2020 Acura MDX engine problems

“On XXX, while operating my vehicle, the engine suffered a catastrophic internal mechanical failure due to a broken connecting rod, rendering the vehicle completely disabled and creating a sudden loss of motive power. This vehicle is a 2020 Acura MDX Tech SH-AWD with a 3.5L V6 engine (Engine Code J35Y5). The failure mode experienced is identical to the crankshaft and connecting rod bearing defect detailed in Acura Recall 23V-751 (NHTSA Campaign Number: 23V751000). However, when checking my specific VIN ([XXX]) on the NHTSA lookup tool, it reports 0 unrepaired recalls. My vehicle was excluded from the original recall population despite carrying the exact same engine type, manufacturing year, and experiencing the exact same catastrophic rod fracture resulting from bearing seizure. Because of this severe mechanical failure, the vehicle is un-driveable and requires a complete engine replacement. I am filing this complaint to document that the vehicle population in Recall 23V-751 was too narrowly defined, and to ensure this vehicle is counted in the ongoing NHTSA investigation regarding un-recalled Honda/Acura V6 engine failures.”

“While stopped at a stop light the auto restart feature engaged and shut the engine off. When the light turned green and I released the brake pedal the engine did not restart and the battery warning light illuminated. As cars were honking I activated my hazards, had to place the car in park and shut off/restart the vehicle. Luckily it restarted and I was able to proceed home. It activated again while stopped to get mail at mailbox and restarted with no issue. Mileage is 42668. Recall 23-001 PGMfi performed 8/2023. Battery replaced 12/2024.”

“My 2020 Acura MDX fails to restart after the Auto Idle Stop system shuts off the engine at stops. The vehicle stalls and will not restart in active traffic, including busy intersections and high-speed roads. This began about three years ago and now happens every day, leaving my family stranded in live traffic lanes at risk of a collision. On [XXX], the engine shut off and would not restart in the middle of the [XXX], with traffic moving around me at about 40 mph. Capitol Acura in San Jose diagnosed a failing starter motor and ordered a replacement under repair order [XXX]. The part has been on backorder since, with no delivery date. I escalated to American Honda / Acura Client Relations on October 13, 2026 (case [XXX]). On [XXX], Acura replied only that it is "still reviewing" my request. No loaner or alternate vehicle has been provided, and no repair timeline has been given. I am concerned this is a defect affecting other MDX owners: a starter that fails under frequent Auto Idle Stop cycling, combined with a parts shortage that leaves unsafe vehicles on the road. I request that NHTSA review this issue for a possible investigation or recall.”

“On multiple occasions while my car is stopped at a light or stop sign the idle restart stalls and the car shuts off. I need to give it a few minutes and restart the car. It mainly happens when the auto shut off for idling restarts. I have had it happen more than 10X with my kids in the car. I have done all required work - timing belt & water pump replacement, transmission fluid flush, new times and new suspension. It continues to get worse.”

“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.”

“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.”