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How Rear Occupant Alert Works and Why You Need It

The growing number of children and pets left unattended in vehicles has given rise to rear-seat occupant alert systems.


In recent years, automakers have introduced rear-seat occupant alert systems to their vehicles. And for many safety advocates, parents, and pet owners, it’s about time.

According to the U.S.-based National Highway Traffic Safety Administration, a child dies in a hot car about every nine days. While The Canadian Veterinary Medical Association says heatstroke can occur surprisingly fast, even when animals are left for only short periods of time in vehicles with the windows partially rolled down.

Read on to find out how the rear-occupant alert systems can help you keep your kids and pets safe, how they work, and how to turn them off, should the need arise.


What is Rear Passenger Alert?

Rear-occupant alerts remind drivers to check the back seat. Many automakers offer a rear-seat reminder system in their 2022 model-year cars. They’ll grow more common in coming years—virtually every automaker has pledged to add a rear passenger alert system to all the vehicles they build by 2025.

Rear-passenger reminders can be as simple as a prompt on a car’s infotainment screen reminding the driver to check the back seat before they leave their car. Or, they can be as complex as ultrasonic sensors that detect movement inside a vehicle after the driver turns it off. It may flash the car lights or sound the horn in response.


Why Rear Occupant Alerts are Useful

It’s never safe to leave a child or a pet unattended in a vehicle. The inside of a parked car can quickly reach unsafe temperatures, even on a mild day. Consumer Reports testing has shown that the interior of a car can reach 40 degrees Celsius—a potentially fatal temperature—after just one hour parked on a 16-degree day. And while this topic may make you think of kids left in cars by accident, we should note that, in 2020, almost two in five hot car deaths occurred when kids got into cars on their own without their parents’ knowledge.

There’s good reason to believe some hot car deaths can be prevented. According to the safety watchdog group kidsandcars.org, the number of hot car deaths began declining during the last three years. We’re aware of no studies explaining the decline. But it comes after several years of awareness campaigns aimed at making sure drivers know the danger of leaving a child or a pet in a hot car.

The decline also comes after a new technology appeared in cars: rear-occupant reminder systems designed to remind or warn drivers that a person or animal may be in the back seat of a parked vehicle. The systems carry titles like Rear Occupant Alert, Rear Seat Reminder, Rear Door Alert, or Rear Passenger Alert.

How Does Rear Occupant Alert Work?

No single standard explains how a rear-seat occupant reminder system works. So, automakers take several approaches to protect kids and pets from being left alone in hot cars.


Screen Reminders

At the simplest level, some cars prompt the driver to check the back seat for passengers every time they turn off their car.


Door Logic Systems

Most systems available in the 2022 model year use a door-sequencing logic. Onboard computers note when a rear door is opened before driving. If a back door isn’t opened soon after you park the car, the vehicle sounds an audible alert and flashes a reminder on the screen or in the driver’s instrument cluster reminding the driver to check for rear-seat passengers.


Motion Detectors

A few cars use a more sophisticated system that detects movement in the rear seat. Hyundai and Kia, for instance, offer a door logic system as standard equipment on almost all their vehicles. They also provide a more advanced system for family-friendly vehicles, like the Hyundai Palisade and Kia Telluride mid-size SUVs. The system uses ultrasonic sensors to detect movement in a parked car up to 24 hours after being parked and sends alerts to the owner’s cell phone.

This approach is rare in the 2022 model year. But it will probably grow more common in future years.


Future Advanced Systems

Automakers increasingly fill vehicle cabins with sensors as our cars grow more automated. Driver-attention monitors are increasing every day. Pointing similar sensors at the rear seats grows more cost-effective every year.

Automakers are also researching more advanced rear-occupant detectors. Hyundai, worried that its ultrasonic sensors could miss a sleeping infant covered in heavy blankets. So the automaker has developed a radar-based sensor that can “measure even minute movements of the chest and blood flow of passengers by passing through their clothes.” That system is not yet offered for sale.


Which Cars Offer Rear-Seat Reminder Systems?

As recently as the 2020 model year, few cars offered a rear-seat reminder system. As the 2022 model year begins, it’s almost easier to list the vehicles that don’t.

Acura, Buick, Cadillac, Chevrolet, Ford, Genesis, GMC, Honda, Hyundai, Infiniti, Kia, Lincoln, Nissan, Subaru, and Toyota all offer a rear-occupant alert system on most or all of their 2022 vehicles.

Those that don’t yet offer a rear-passenger alert will do so soon.


Is Rear-Occupant Alert Mandatory?

Several trade associations represent the auto industry. Many manufacturers are members of more than one. The two largest—the Alliance of Automobile Manufacturers and the Association of Global Automakers—made a joint commitment to add a rear-passenger alert system to every car by the 2025 model year.

Together, the two groups represent nearly every manufacturer selling cars in Canada today, outside of exotic car builders (and few exotic cars have rear seats). Tesla does not disclose its membership in trade associations. But the company has sought regulatory approval for a millimetre-wave radar system to detect occupants in a parked car, so we assume Tesla will soon introduce its version of a rear-occupant alert system.

The law doesn’t require rear-passenger alerts yet, but it may soon. The iIn the U.S., the House of Representatives has passed a bill to require the systems in all cars. A companion bill has not yet advanced in the Senate.


Can Rear-Passenger Warning Be Disabled?

The rear-occupant alert system on most 2022 model year cars can be disabled. In some cases, this is done through a simple switch. In others, it requires paging through several menus on a car’s touchscreen. Consult your vehicle owner’s manual for instructions on turning the system off in your car.

But remember, these systems wouldn’t exist if there weren’t a tragic reason for them. Consider that you may be better off letting it annoy you into checking the back seat often.


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