A week before Fiat Chrysler is schedule to answer for its perceived lackadaisical attitude toward 22 recalls, federal regulators announced they’ve opened a separate investigation into one of the car maker’s vehicles: the Dodge Dart.

The National Highway Traffic Safety Administration’s Office of Defects Investigation opened an inquiry into nearly 121,000 model year 2013 Dodge Dart vehicles after receiving 18 consumer complaints regarding braking issues.

According to a notice [PDF] from NHTSA, the complaints revolve mainly around issues in which the brake pedal can suddenly become hard to depress, leading to the need for an unexpectedly long braking distance.

Some of the drivers who submitted claims to NHTSA say they heard a “popping” or “hissing” sound when applying the brake, followed by a hard pedal feel and reduced brake effectiveness.

“My son was driving and he parallel parked so he could run into a store,” one complaint states. “When he returned he put it in gear and signaled to pull out. Suddenly, there was a loud popping sounds and what sounded like air whooshing out of the brake pedal. He attempted to apply the break and he said it felt like something was stopping it from going down.”

In several cases, Dart owners say they were driving at moderate rates of speed when the issue occurred and had to apply the emergency brake in order to come to a stop.

“While driving at approximately 40 miles-per-hour, the vehicle did not come to a complete stop when the brakes were depressed,” another complaint states. “The contact had to shift into a lower gear, apply the brakes and then the emergency brake.”

“When I was coming off of a highway, I tried to brake and my brake sounded like it accumulated air and then I heard a pop,” a Dart owner recalls. “The brake went stiff and I could not use the brake. My car kept on going at 50 miles-per-hour and I could not use my brake. Luckily enough I used my hand brake to stop myself and avoid a crush into a busy street.”

Some owners say that after the issue a dealer replaced the brake booster and master cylinder in order to correct the problem.

NHTSA’s preliminary evaluation will assess the scope, frequency and safety-related consequences of the alleged brake defect. An investigation can, at times, lead to a recall.

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