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B0105 — Sensor Cleaning Air Blower Actuator B Control Relay

Generic OBD-II · all makesBody

B0105 indicates a problem with the control circuit for the air blower actuator used to clean a sensor, typically found in climate‑control systems.

Symptoms

What causes it — most likely first

1. Blown fuse

A fuse dedicated to the blower actuator circuit can open due to overload or a short, cutting power to the relay.

2. Faulty control relay

The relay that switches the actuator on can fail internally, preventing the blower from receiving power.

3. Wiring or connector issue

Corroded, damaged, or loose wiring/connector pins can interrupt the signal from the PCM to the relay.

4. Blower actuator failure

The actuator motor or its internal switch may cease to operate, causing the circuit to appear faulty.

5. Powertrain control module (PCM) output problem

A rare scenario where the PCM does not provide the correct control signal, typically only after other components are verified.

How it's diagnosed

  1. Locate and inspect the fuse for the blower actuator circuit; replace if blown.
  2. Test the control relay for continuity and proper operation; replace if defective.
  3. Check voltage at the relay output and actuator terminals while the system commands activation.
  4. Inspect wiring harnesses and connectors for corrosion, damage, or loose pins.
  5. If power and ground are present at the actuator but it does not run, test the actuator itself for failure.

Code facts & related codes

SystemBody
StandardizationSAE generic — identical on every make
Related codesB0100 — Sensor Cleaning Air Blower ActuatorB0101 — Sensor Cleaning Air Blower Actuator BB0102 — Sensor Cleaning Air Blower Actuator CoB0103 — Sensor Cleaning Air Blower Actuator B B0104 — Sensor Cleaning Air Blower Actuator CoB0106 — Lidar Washer Actuator

Vehicles this code applies to

The definition is universal; the diagnostics are engine-specific. Open your vehicle for the codes documented for it:

2014 BMW 328d2014 BMW 328d xDrive

Frequently asked

Do I need to replace the PCM to clear B0105?

No, the PCM is rarely the cause; most often the issue is a blown fuse, bad relay, or wiring problem that can be repaired without PCM replacement.

What tools are required to diagnose this code?

A multimeter or test light, basic hand tools, and a wiring diagram for the specific vehicle are sufficient to verify power, ground, and signal at the relay and actuator.

Is this code related to the HVAC system?

Yes, it involves the air blower actuator that is part of the climate‑control system used for sensor cleaning.

How long does a typical diagnosis take?

Usually 30–60 minutes to verify fuse integrity, relay function, wiring continuity, and actuator operation.