2021 Acura RDX

My 2021 Acura RDX A-Spec AWD had approximately 89,000 miles when this incident occurred on [October 23rd] on I-10 in Tempe Arizona]. My wife was driving when the vehicle displayed emissions and brake-system warnings, lost power and slowed unexpectedly. She was unable to restart it at that time. The unexpected loss of power in freeway traffic created a safety concern. I was subsequently able to drive the vehicle to the dealership. Acura of Tempe inspected the vehicle. Its written diagnosis reported an “ENGINE TEMP HIGH” warning, misfires after the vehicle had been sitting, an empty coolant reservoir and low radiator coolant. The dealer diagnosed a head gasket leaking coolant into a cylinder and recommended head gasket replacement, with further inspection for cylinder-head damage. The dealer provided an approximately $4,000 repair estimate, with potential additional costs depending on the cylinder-head findings. I am reporting the unexpected loss of power and the diagnosed coolant intrusion as a potential safety defect. I can provide the dealership’s written diagnosis and estimate. Approximate speed at the time: 65 MPH. Crash, injuries or fire: [None. Current repair status: [not repaired ].

NHTSA ID

11774425

Incident

Oct 23, 2026

The contact owns a 2021 Acura RDX. The contact stated that the front passenger’s side seat belt retractor failed to retract as needed. The vehicle was taken to a dealer and was inspected and repaired. The failure mileage was 42,000

NHTSA ID

11772643

Incident

May 1, 2026

Mileage

42,000 mi

Rear window shattered spontaneously twice. 9/12/24 & 10/11/26

NHTSA ID

11770672

Incident

Oct 11, 2026

2021 Acura RDX has cold start, uses coolant and will stumble, limp mode approaching 2000 RPM. Vehicle will flash check engine light and then will go away when vehicle is restarted. Using search criteria noted TSB issued for same make model and year with an extended warranty being offered through TSB, 10 year 150,000 miles. Vehicle has 103,000 miles. Dealer is stating no TSB for this VIN, however the number one issue noted through internet searches and this database.

NHTSA ID

11769725

Incident

Sep 21, 2026

Acura Sunnyside in New Hampshire denied to repair my recall on my 2021 Acura RDX.

NHTSA ID

11768303

Incident

Oct 1, 2026

Engine was replaced 12/13/25 due to cracked cylinder head causing oil to leak into exhaust and fill cylinder 2 and 3. 09/21/26 new engine replacement done in December 25, has now blown cylinder head gasket seal in under 12,000 Miles. Causing coolant to leak into cylinders 2 and 3.

NHTSA ID

11766897

Incident

Sep 20, 2026

Head Gasket blown known problem with Honda and Acura 2.0T I didn’t know of this issue until it occurred to Loi Me in 2025 My Acura dealership told me it’s a huge problem with the Acura RDXand it should be a warranty extension similar to the warranty extension for other Honda products done in August 27, 2026 I was lucky and my head gasket didn’t blow while I was driving I’m also concerned that it’s gonna happen again I’m not sure if the problem was resolved with the new head gasket or it’s a stomach problem with the motor that has not been addressed yet

NHTSA ID

11766372

Incident

Sep 1, 2025

Two low-speed sudden unintended acceleration events while parking a 2021 Acura RDX. Incident 1 (July 2026): While parking at low speed, the car unexpectedly surged forward. Flew up the curb and hit a restaurant window, causing massive undercarriage damage. Active braking did not help and seemed to make acceleration worse. It only stopped when it wanted to. Incident 2 (August 2026): Two weeks after getting the car back from repairs, under identical low-speed parking conditions, a second sudden acceleration event occurred. Slamming on the brakes did nothing. It stopped after scraping a car wash vacuum pole, destroying the entire passenger side. Prior to these, the car exhibited erratic safety software behavior, including multiple phantom braking incidents where it slammed on its brakes violently with no obstacles present. I bought the car Certified Pre-Owned two years ago. The dealership repaired a known "popping sound" from the panoramic sunroof frame three times. This required extensive cabin/pillar teardown work, which may have disturbed internal wiring harnesses or grounding points linked to the electronic throttle control system. In both events, it felt like an uncontrolled amusement park ride—the engine loudly revving and taking over with zero driver control. I initially assumed pedal confusion during the first crash, but since it happened again under identical circumstances, there is clearly a systemic electronic/software defect in the Throttle Actuator or Powertrain Control Module. The vehicle is at an insurance network body shop awaiting forensic evaluation of the throttle system, pedal sensors, and a Bosch EDR black box download.

NHTSA ID

11758797

Incident

Aug 19, 2026

Over The Air Update - Vehicles equipped with the System Updates application are capable of downloading and installing Over the Air System Updates. System Updates contain upgrades that fix a variety of operational errors and/or enhancements that add new functionality. Information for the various software releases can be found in this document. Software version: D.1.6.4

"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."

Service Bulletin - Oil leak at the cam chain tensioner inspection cover due to and insufficient sealant adhesion on the inspection cover.

Service Bulletin - The front and/or rear brakes make a high-pitched squeal when the brakes are lightly applied at 24 km/h (15 mph) or less, with ambient temperatures below 10°C (50°F).

Service Bulletin - The front and/or rear brakes make a high-pitched squeal when the brakes are lightly applied at 24 km/h (15 mph) or less, with ambient temperatures below 10°C (50°F).

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.