— An Acura ILX master cylinder failure investigation has been closed after the automaker recalled the vehicles.
The National Highway Traffic Safety Administration opened the investigation in October 2025 following complaints from 2019-2020 Acura ILX owners.
The complaints allege the ILX master cylinder failures caused the brake pedals to fall to the floorboards, and some owners complained the brake pedals felt soft and needed to be pumped to stop the vehicles.
Honda/Acura investigated the complaints and found residual plasticizer in the brake reservoir hose which could contaminate the brake fluid. This contaminated brake fluid was absorbed by the secondary cup seal which caused the seal to swell.
The engine heat from the Acura ILX also expanded the swollen seals which allowed brake fluid to bypass the master cylinder cup seals. The leaking brake fluid created soft brake pedals or pedals that fell to the floors. The condition caused extended stopping distances which increased the crash risk.
In December 2025 Acura announced a recall of every 2016-2020 Acura ILX built from October 9, 2014, to January 29, 2020. At that time Acura had received 192 master cylinder warranty claims going back to 2016. However, there were no reports of injuries or deaths.
Acura owners of about 70,000 ILX vehicles were told the master cylinders would be replaced. The replacements are made with better inner cup seals to prevent brake fluid leaks.
NHTSA closed its Acura ILX investigation based on the master cylinder recall but will continue to monitor the field for additional complaints.
