B0100
Driver Door Lock Cylinder Switch Circuit
The body control module has detected a fault in the driver door lock cylinder switch circuit. This switch detects key rotation in the door lock and is used for keyless functions and the alarm system.
- Check engine light: Not always
- Emissions related: No
- Repair difficulty: medium
Symptoms
- Warning light or symbol related to the affected system
- Comfort or safety function impaired
Common causes
Ordered by how often each turns out to be the cause.
- Lock cylinder switch failedCommon
- Door harness broken in door hinge areaPossible
Parts involved
- Door Lock Cylinder Switch
- Body Control Module
- Door Harness
B0100 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.