Honda (HMC) may be heading toward an enormous recall of its vehicles in the near future.

The National Highway Traffic Safety Administration (NHTSA), the US automobile safety agency, has opened a preliminary investigation into safety issues affecting 1.72million Honda CR_V and HR-V SUVs.

The probe is examining reports of a sudden loss of power while traveling at highway speeds which occurs without any warning. NHTSA field reports have attributed the loss of power to, “differential seal leaks resulting in rear differential lock-up.” The rear differential controls the speed of the two rear wheels relative to each other, allowing them to vary when making turns, when one wheel needs to turn slightly faster than the other around the outside radius of the turn.

The NHTSA notes some of the rear differential lockups actually shattered the vehicle’s driveshaft while it was traveling at highway speeds.

In a written statement Honda said, “We’re aware that the NHTSA has initiated a Preliminary Evaluation regarding reported issues with rear differentials in 2018-2022 CR-V and HR-V vehicles equipped with all-wheel drive. Honda will cooperate with the NHTSA through the investigation process, and we will continue our own internal review of the available information.”

NHTSA investigations usually precede the agency forcing automakers to initiate a recall. As a result, automakers will often respond to such an investigation by initiating a recall themselves.

This is the second NHTSA investigation of a Honda vehicle this year. In June, NHTSA opened an investigation looking at inadvertent activation of Honda’s automatic emergency braking feature. It affected approximately 1.7 million Honda Accord and CR-V models. That investigation is still ongoing, and no action has been taken yet.