Body, generic

B0105 Sensor Cleaning Air Blower Actuator B Control Relay

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

B0105 is the relay fault on the B side of the sensor-cleaning air supply. If B is a compressor rather than a small fan, as in Uber's patent where a compressor charges an accumulator and recharges once pressure drops to roughly 130–140 psi, the relay carries a sizable inrush current, and pitted contacts become the usual weak point. HELLA lists change-over and make relays for motors such as fans and names the checks: dropout voltage, contact drop, coil resistance. AUMOVIO stresses that air keeps a lidar usable in bad weather by blowing off droplets, so a stuck relay shows up first in rain. No carmaker has published B0105 or what B supplies.

Likely causes

Contacts of relay B pitted by high motor or compressor inrush current
Relay B coil or its suppression diode failed
Corroded relay socket or wrong relay type fitted

Symptoms

  • Blower or compressor B does not start, or will not switch off
  • Droplets stay on sensor windows in rain
  • Assistance functions drop out when a sensor is reported blocked

Repair estimate

DifficultyEasyDIY possible
Parts and labour€20–250
Time0.2–1 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

sensor cleaning air blower relay brelay control circuitsensor cleaning air blower b

Related codes

B0101B0103B0104

References: hella.com, patents.google.com, aumovio.com.