B0540
Driver Door Ajar Switch Circuit
The driver door ajar switch circuit is reporting an implausible signal. The interior light may stay on or door open warning may be incorrect.
- Check engine light: Not always
- Emissions related: No
- Repair difficulty: easy
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.
- Corroded door switch / strikerCommon
- Wire break in door harnessPossible
Parts involved
- Driver Door Ajar Switch
- Body Control Module
B0540 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.