Driver-assistance systems rely on forward cameras, radar sensors, surround cameras and ultrasonic parking sensors. These feed automatic emergency braking, lane keeping, adaptive cruise control and blind-spot monitoring. They are safety systems, and buying one used carries an obligation that does not apply to most parts: it must be calibrated after installation.

Calibration is not optional

A camera or radar sensor reports what it sees relative to where it believes it is pointing. A few millimetres of mounting difference, or a fraction of a degree of angle, moves the system's picture of the road by a large amount at distance. A sensor that has been replaced but not calibrated may still appear to function while acting on a wrong picture - which is a worse outcome than a system that is plainly disabled.

Calibration is a defined procedure, and depending on the vehicle it is:

  • Static: performed in a workshop with specific targets at measured distances, on a level floor, with the vehicle at a defined ride height. This needs space and equipment not every shop has.
  • Dynamic: performed by driving a defined route at defined speeds with a scan tool connected.
  • Both, on many vehicles.

Find out before you order which your vehicle requires, who locally can do it, and what it costs. That figure often changes whether a used sensor saves anything at all. Our programming guide explains why calibration is a distinct operation from coding or flashing.

Related work that also triggers calibration

Calibration is required not only when the sensor is replaced. On many vehicles it is also needed after a windscreen replacement where the camera mounts to the glass, a wheel alignment, suspension or ride-height changes, or front-end bodywork. If you have had any of those done and an assistance system has been behaving oddly, mention it - the sensor may be fine.

What to check on used sensors

  • Lens and radome: the plastic cover of a radar sensor and the lens of a camera must be undamaged and unpainted. Repainting a radar cover, or a bumper in front of one, with the wrong material can affect the signal.
  • Mounting bracket: unbent and undamaged. The bracket sets the aim, so a distorted one may not calibrate.
  • Connectors: clean, straight pins, no corrosion.
  • Housing: no cracks or water ingress. These sensors live in exposed positions.
  • Accident history: ask directly. A sensor from a front-damaged vehicle may have taken an impact that is not visible.
  • Part number and software level: these change frequently, and a mismatch may not calibrate.

Parking sensors specifically

Ultrasonic parking sensors are simpler and cheaper, but note that they are frequently colour matched to the bumper and that a repainted sensor - particularly one with thick paint - can behave erratically. False alarms are also commonly caused by dirt, ice, a wet bumper or a single failed sensor dragging the whole array down, rather than by the module.

Before you commit

Confirm the part number and software level, the mounting bracket condition, the donor vehicle's accident history, and who will calibrate the system and at what cost. Our return policy lists electrical and electronic parts as non-returnable once installed, tested or connected, so the specification and the programming path need to be settled before the part is fitted rather than after. Our 30-day limited warranty (up to 90 days on select parts, where your quotation says so) covers the part itself, not labour, installation, diagnostics or any other repair cost. Returns must be requested within 7 calendar days of delivery and need a written RMA from us before anything is sent back.

Use the camera module quote page, the radar sensor quote page, the parking sensor module quote page, or the part request form with your VIN.