Sveriges Volvoforum

Check the following possible fault causes and corresponding actions for false warnings.

Cause: The sensor or sensor cradle is dirty.
Action: Cleaning sensor and cradle.

Cause: Dirt or water has penetrated between the sensor and silicone ring.
Action: Cleaning sensor and silicone ring.

Cause: Water build-up behind sensor.
Action: Clean drain hole in sensor cradle rear. Check whether water or dirt has penetrated between the sensor and silicone ring around the sensor membrane, if so, clean here as well.

Cause: Loose connection between the sensor and cable.
Action: Connect sensor and cable harness.

Cause: The cable is not naturally routed.
Action: Correct the cable or replace cable harness and check that the cable is long enough.

Cause: The sensor is not centered (middle of the hole on visible surface).
Action: Reinstall the sensor with silicone ring centered in the sensor hole on the bumper.

Cause: Sensor and sensor cradle are loose or have detached.
Action: Secure the sensor or bond the holder.

Cause: The silicone ring around the sensor is askew or missing
Action: Install the silicone ring around the sensor or correct the silicone ring.

Further actions if the sensor still does not work:
Use soft material to cover the object or sensors suspected to give a false warning during fault tracing. This can expose the sensor causing the false warning or which the object that may be the reason for the ultrasound bouncing back to the sensor with a false warning as a result. Especially if accessories are installed around the sensors (e.g. tow hitch, auxiliary lights etc.).

Replace with another sensor in the bumper to check where the fault is (sensor or cable). This is to determine whether the fault follows the sensor or remains at the same position.