Parking Sensors – What, Why & How?

Parking Sensors – What, Why & How?

At some point the majority of drivers, whether they’re young or old, will experience difficulty in parking perfectly. It could be due to how someone else has parked or being rushed by traffic as you try to parallel park on the high street.

Whatever the excuse you come up with (and I’ve made a few myself on the odd occasion), you probably end up thinking to yourself, “I wish I had some parking sensors”. Once the realm of high end, expensive, cars. These high tech, high pitched, devices can now be retrofitted to almost any car, but with so many options to choose from what type of parking sensors should you get?

What Are Parking Sensors?

Parking sensors are great little devices that are usually installed into a vehicles rear bumper and activated when the vehicle is shifted into reverse. Their main purpose is to alert you to anything that is behind a vehicle whilst it is reversing.

Why Should You Have Parking Sensors?

Lots of modern vehicles have large blind spots that can make parking and turning difficult. Parking sensors are great at helping you reverse into tight parking spaces, as well as alerting you to anything that may be behind your vehicle such as high pavements, bollards, other vehicles and small children. Although they may be slightly annoying, due to their high pitched shrill, they are great at preventing avoidable knocks to a vehicle.

How Do Parking Sensors Work?

There are three main types of rear parking sensors:

1-Ultrasonic Sensors
2-Rear Facing Cameras
3-Electromagnetic Sensors

Ultrasonic Sensors

These are the most common type of parking sensor and are usually embedded within the rear bumper of a vehicle. You’ve probably noticed lots more vehicles sporting these small circular devices (usually 4 or 6 across the bumper) that tend to be the same colour as the bumper of the vehicle. This type of sensor works on the same principle as naval sonar devices. By emitting high frequency sound waves and measuring how long it takes to come back to the sensor it can inform you of how close you’re getting to an obstacle.

This type of sensor usually has two forms of informing you how close you are to an object. The first is to ‘screech’ louder and louder until you stop. The second way is via a visual readout that usually works alongside the audible warning.

Rear Facing Cameras

These work by giving you a live feed to the infotainment screen on the vehicle once you shift gears into reverse. You can also get rear facing camera kits that link to an app on your smart phone. Although this type of device is great at providing you with an actual live image of where you’re going, they can be expensive optional extras, unless you fit one yourself. They can also provide a limited view depending on the type of lens and placement of the camera. Additionally they can suffer from poor quality ‘night vision’ modes.


Electromagnetic Sensors

These are probably the least common type of parking sensor available on the market. Installed behind the bumper itself, they work by creating an electromagnetic field around the rear of the vehicle and sound a warning when it senses a disturbance within the electromagnetic field.


Although this is possibly the most discreet option of the three parking sensors, it is also arguably the least reliable, as it relies on the vehicle moving very slowly to detect changes within the electromagnetic field before sounding a warning.

Always remember that reversing is all about spatial awareness, knowing the size of your vehicle and utilising your mirrors. Yes, parking sensors are a great aid giving you additional information and confidence, BUT, you should never rely solely on them!