Code Definition

B2104 — Door Passenger Key Cylinder Switch Failure

System: Body  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About B2104

B2104 is a generic (obd-ii standard) body diagnostic trouble code. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

Scanning & clearing: Body (B) codes are often stored in the body control module, airbag module, or climate module. A basic OBD-II tool usually will not read body codes — an enhanced or OEM-level scan tool is typically required.

Because B2104 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The Body Control Module (BCM) monitors the passenger door key cylinder switch as part of the central locking and anti-theft system. DTC B2104 is set when the BCM detects an electrical fault in the switch circuit, such as a stuck switch, an open circuit, or a short to ground that prevents the switch from indicating a key turn correctly. The key cylinder switch tells the BCM when the key is rotated in the passenger door lock, allowing the locks to operate manually if the central locking system or remote fob fails. When this code is set the driver may notice the passenger door not responding to m...

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