Code Definition

B1559 — Door Lock Cylinder Circuit Failure

System: Body  |  Type: Manufacturer-Specific  |  Make: Generic

About B1559

B1559 is a manufacturer-specific body diagnostic trouble code. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B1559 is stored, the module has detected an electrical-circuit fault in the wiring, connector, or driver associated with the named component.

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.

B1559 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The B1559 code is set by the Body Control Module (BCM) when it detects a failure in the door lock cylinder switch circuit. The door lock cylinder switch is an electrical contact built into the driver or passenger door key barrel that signals the BCM when the key is inserted and rotated to lock or unlock the doors. The BCM monitors this circuit to control central locking, keyless entry confirmation, alarm disarm, and panic functions, and sets B1559 when the input does not match expected switch states or shows an electrical fault. Symptoms can include the door not locking or unlocking when the k...

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