DTC C1A05-21: Left Rear Height Sensor - Signal amplitude < minimum: Action

NOTE: If any height sensor fixings were slackened or found to be loose or if a height sensor was changed, the vehicle ride height MUST be re-calibrated

Inspect height sensor for damage or loose fixings. Confirm that the correct height sensor part number is installed, as specified in the service parts database
To check height sensor: disconnect electrical connector to height sensor and inspect connector pins and terminals for evidence of corrosion or water ingress. If no corrosion found, disconnect harness at control module and follow steps below
Check for short circuits between any of the three terminals and vehicle ground. Repair circuit as required
Check for electrical continuity between the two connectors for each of the three terminals. Repair circuit as required. Reconnect electrical connector at control module only
Check voltages at terminals within height sensor connector (with sensor not connected): voltage to sensor ground connection should be ~0V, voltage to sensor signal connection should be ~0V, voltage to sensor supply connection should be ~5V. All voltages should be within ± 0.15V. Repair circuit as required, clear the DTCs and retest
To check sensor operation on the vehicle: Check for water ingress around the height sensors, electrical connectors or shaft end. Check for excessive movement in the shaft in all directions. Raise vehicle (ideally on wheels-free ramp) until suspension on corner under investigation is at full extension to gain access to height sensor. Access may be improved by removing road-wheel. Carefully disconnect the height sensor link from the upper suspension arm. Monitor the height sensor signal voltage output for the height sensor under investigation. Position the sensor arm so it is in the mid position and confirm that the voltage is around 2.5 volts. Move the sensor arm over the range ±40° around the mid position and confirm that the voltage changes smoothly between around 0.2 volts and 4.8 volts. If voltages are incorrect or do not change smoothly then renew the sensor.
NOTE: For angles of movement beyond ±40°, the sensor signal will remain at a voltage of ~0.15V or ~4.85V, depending on position of sensor lever. This is normal. When investigation is complete, install the height sensor link to the upper arm. If any fixings to the height sensor body or mounting bracket were slackened, found to be loose or if a height sensor was changed, the vehicle ride height MUST be re-calibrated. Refer to the relevant service information for the calibration procedure