Tesla is issuing a voluntary recall for Model S and Model X vehicles made between February 2016 and October 2016, for a potential manufacturing issue in which the parking brake, once engaged, might experience a fractured internal gear that results in it being stuck in the ‘on’ position.

Tesla stresses that this recall is being done only because the carmaker typically exercises an abundance of caution in these cases, and that only a small number of vehicles will likely ever exhibit the issue, and that even when they do, the resulting problems don’t present a safety risk to either drivers or passengers.

The problem came to light because Tesla found customers were getting alerts that said their parking brake needs service, or that the brake could not be disengaged, not in huge numbers but with noteworthy frequency. Tesla traced the problem back to a batch of brakes from supplier Brembo installed on cars made during the roughly ten month period covered by the recall.

That amounts to around 53,000 vehicles in total, distributed to customers globally, but Tesla says that under 5 percent – perhaps even as low as 2 percent – of those cars actually have the problem. Still, it is opting to recall them all to avoid any potential issues since it’s hard to easily tell which gears are affected and which are not. Parts will be swapped in every case, as a result, and the recall ultimately affects more than half the cars Tesla produced in 2016, per its own financial results.

Tesla will be filing the recall with NHTSA, and expects to have all parts needed to make the swap by October of this year. The process takes less than 45 minutes to replace both of the parts on each brake on the vehicle, but because of availability of replacement parts, the carmaker will be starting the recall process now and complete a total recall by October, assuming all 53,000 vehicles affected come back for service.

Here’s the full email being sent out to Tesla customers this morning describing the problem, and the steps owners can take to get it fixed: