Instructions for a Parking Sensor

Written by spanner spencer
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Instructions for a Parking Sensor
Parking sensors are equipped with either two or four sensors installed evenly along the bumper. (blue car image by Thierry GUIMBERT from

A parking sensor uses small ultrasonic devices mounted on the car's bumper to detect the distance to nearby objects. The parking sensor then emits a beeping noise while the car is in reverse, which increases in frequency the closer the car gets to an object. The benefit of using a parking sensor is that it helps you avoid collisions in areas of low visibility and can help drivers fit their cars into parking spaces they otherwise wouldn't be confident to attempt.

Skill level:

Things you need

  • Vehicle owner's manual
  • Drill
  • Hole saw
  • Half-round file
  • Tape measure

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  1. 1

    Measure the length of the bumper and divide the measurement by half, or in quarters, depending on whether you are fitting two or four sensors. Consider the shape and contours of the bumper and mark the positions of the sensors so they are evenly spaced and will be mounted parallel to the floor. Ensure the shape of the bumper won't leave any of the sensors pointing upward or downward as this will affect their operation.

  2. 2

    Drill the mounting holes for the sensors in the bumper, using a suitably sized hole saw for your make and model of ultrasonic sensors. Clean the holes using a half-round file and install the sensors in the bumper.

  3. 3

    Connect the sensors to the control box as detailed in its instruction manual. Fit the control box in the boot of the car, in an unobtrusive position. It needn't be permanently fixed to the bodywork, so long as it isn't left loose in the boot. Positioning it behind the moulding along the left or right bulkhead of the boot will hold the control box securely without requiring you to drill holes.

  4. 4

    Position the parking sensor's sounder so it is audible throughout the car. Generally, the sounder is loud enough that it can be installed in the boot. If the control box is behind the moulding, the sounder should be positioned outside the moulding to ensure it remains audible.

  5. 5

    Consult the car owner's manual and find a connection for its reversing light. Power for the control box should be derived from this connection, so the sensor is activated only when the car is put in reverse. The negative power connection from the control box can be derived from any ground connection on the bodywork.

  6. 6

    Switch the engine on and put the car in reverse. While keeping the car stationary, have an assistant walk up to each of the bumper-mounted sensors in turn to test whether each one is operational.

Tips and warnings

  • Don't rely solely on the parking sensor while reversing.

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