Connecting your phone to your vehicle via a Bluetooth link can make driving safer. But for thousands of Acura owners, they claim this convenience — a HandsFreeLink Bluetooth phone-pairing system — contains a defect, that results in dead car batteries and the need for frequent battery replacements. Today, those owners came together to file a class-action lawsuit against Honda, the maker of the vehicles.

The complaint [PDF], filed in the U.S. District Court for the Northern District of California, claims that Honda continued to sell Acura vehicles with the battery-draining defect despite knowing about the issue nearly 11 years ago.

According to the complaint, the HandsFreeLink unit found the vehicles can get stuck in the “on” position, even if the feature is not in use or the car’s engine is turned off.

As a result, the HandsFreeLink creates a constant drain on the electrical system, leading to drained and dead batteries, recurring battery replacement, and premature failure of other electrical components of the vehicle, including the alternator.

“Acura owners are faced with the choice of expensive replacement of the HandsFreeLink unit, with no promise that the replacement also will not get stuck ‘on,’ or disabling the HandsFreeLink system by disconnecting the HandsFreeLink unit from the car,” the complaint states.

Because of the issue, and costly options for repair, the lawsuit argues that owners have found themselves with vehicles that are less valuable than comparable cars with properly functioning hands-free systems.

The suit claims that Honda has been aware of the issue since 2005, but has failed to do anything to fix the problem.

“Honda has merely issued internal Service Bulletins to its dealers over the years, notifying only the dealers about the problem, but offering no meaningful solution, warranty coverage or recall,” the lawsuit states.

The carmaker, in a rush to be the first company to offer hands-free calling with HandsFreeLink, failed to ensure the unit would reliably switch off, and also failed to adequately notify owners of the issue or remedy the problem.

In fact, the lawsuit cites complaints from vehicle owners posted on the National Highway Traffic Safety Administration’s database, that include incidents where the vehicle unexpectedly loses power while driving at high speeds.

“While driving 65 mph, the vehicle [a 2007 Acura TL] stalled and all of the warning lamps illuminated,” the complaint reads. “The vehicle was towed to the dealer. The technician diagnosed that the HandFreeLink failed, causing the battery to drain. As a result, the alternator and HandsFreeLink needed to be replaced.”

“When I started the vehicle [2006 Acura TL], it has a moaning sound,” another owner writes. “I continued driving and the battery light, airbag light, CSV light, all came on just before the dash lights flickered on and off, then totally went out and the car engine shut off. When I tried to jumpstart the car, the car started after a few minutes, but when the jumper cables were removed, the car instantly shut down. This is the third battery this car has had.”

“Related to the HandsFreeLink, which hasn’t worked in two years. I have replaced the battery several times, once twice in one week,” the owner of an Acura MDX writes. “I replaced the battery a week go and asked them to please reset the HandsFreeLink, and the car navigation flickers now. Two days ago the car momentarily lost power while I was driving.”

With the lawsuit, owners seek reimbursement related to the defect and an injunctive order to end Honda’s concealment of the defect and denial of warranty coverage for repairs related to the HandsFreeLink defect.

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