Code Definition

B2108 — Trunk Key Cylinder Switch Failure

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

About B2108

B2108 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 B2108 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 trunk key cylinder switch as part of the central locking and vehicle security system. DTC B2108 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 trunk key cylinder switch tells the BCM when the key is rotated in the boot or trunk lock cylinder, allowing the trunk to be opened manually when the central locking system or remote release fails. When this code is set the driver may notice the trunk failing t...

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