The US safety regulator – the National Highway Traffic Safety Administration – will open a preliminary investigation into a possible defect on the 2014 Chevrolet Impala.

According to the agency, the probe is investigating whether the emergency braking system on General Motors Impala has a defect. The issue has been reported by a driver who said his car’s system activated more than once without prior notice.

The system involved is called an autonomous braking system, which is a safety feature that is becoming increasingly popular among carmakers – the system activates without driver input the brakes if, in certain situations, the vehicle is in danger of hitting another vehicle or an object.

“The consumer alleges that the driver assist system inappropriately activated emergency braking, bringing the vehicle to a complete stop under what the driver considered to be full braking force,” a NHTSA report said.

According to the NHTSA the driver experienced the situation in more than one occasion – and in one of the instances his Impala was cruising at around 40 mph (65 km/h) when the system activated although no car was in front – causing the vehicle to stop and get struck by the car behind – luckily no injuries occurred in the accident.

The NHTSA is now assessing the problem and investigates to see if other vehicles were affected. Chevrolet built for the US around 60,000 Impala cars of the 2014 model year.

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