Car owners guide to: Car Accessories > Parking Sensors

Dents to the bumpers or underbody panels can happen all too easily when parking in unfamiliar places, thanks to low walls, high kerbs and bollards. Far worse is the chance of a child stepping out behind you to cross the road as you are about to reverse. It may come as a surprise to learn that as many as one-third of all vehicle accidents are caused by driver miscalculation or being unaware of objects and people around the vehicle when parking or reversing. Parking sensors make driving both easier and a good deal safer.

Sensors are mounted at the front and rear of the vehicle and these gauge the proximity of objects and give out an audible warning as you drive closer to them. These are now appearing as a factory-fitted item on some vehicles but are also available as an aftermarket fitment. Not only do they make parking less stressful and safer, they could pay for themselves in a short time. The excess on your vehicle insurance usually means you'll end up paying the full cost of any relatively minor damage, or it could mean the loss of no claims bonus or a personal injury claim.

Few of us might admit that we feel uncomfortable having to park in tight spaces. A set of parking sensors won't correct bad technique but will help to make the average driver more confident, and the reduction in stress level alone makes it worthwhile!

Parking and reversing sensors using electromagnetic sensing

There are two main types of sensors - Ultrasonic & Electromagnetic Systems

Ultrasonic sensors emit a signal that gets reflected back off any nearby obstacles. The closer the sensor gets to the object, the quicker the reflected signal reaches the sensor. A circuit is activated to give an audible warning, usually a similarly quickening beat.

Electromagnetic systems work by creating an electromagnetic field in the vicinity of the sensors. Any object that intrudes into this invisible 'force field' triggers a warning.

The Ultrasonic type is far more common but the Electromagnetic systems offer a preferred alternative in some situations. With Ultrasonics, it is necessary for the sensor to have clear vision, which usually means that holes must be drilled in the bumper.

Electromagnetic Parking Sensors do not look for a reflected signal, instead they create a wide electromagnetic force-field and this can extend through and beyond the car's body panels. For this reason, this type of sensor can be fitted behind the bumper so that no externally visible alteration is required, although the bumper and/or underbody panel may need to be removed in order to fit the system.

Benefits of the electromagnetic system over ultrasonic sensor systems include:

  1. > The sensors are compact and can be fitted without drilling the vehicle's bumper. Maintains your car's original factory look and improves its resale value.
  2. > Electromagnetic systems provide a wider operating zone around, above and below the bumper.
  3. > The extended coverage allows it to detect low and high kerbs, small and large objects, people as well as solid fixed objects.
  4. > Excellent close proximity detection - distances as short as 10cm (4 inches) can be accurately detected, allowing you to park in tight spaces with confidence.
  5. > Compatible with vehicles that have a tow bar, towing hook, spare wheel or other external item fitted.

This type of parking sensor system is also highly recommended for vehicles fitted with externally mounted wheels or accessories - a spare wheel on the back of a 4x4, for example, or a cycle rack. These can cause false triggering or inaccurate warnings when used with ultrasonic systems. Electromagnetic systems ignore fixed items that are already present and look for changes to the surrounding area. This makes the electromagnetic systems generally much better suited to 4x4s, MPVs, SUVs, vans and motorhomes.