C0205
Stop Lamp Switch Circuit
The ABS or stability control module has detected a fault in the stop lamp switch circuit. The brake light switch tells the module whether the driver is braking and is used to coordinate ABS, traction control and cruise control.
- Check engine light: Not always
- Emissions related: No
- Repair difficulty: easy
Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
Common causes
Ordered by how often each turns out to be the cause.
- Stop lamp switch failed or misadjustedCommon
- Wiring or connector faultPossible
- Blown stop lamp fuseLess likely
Parts involved
- Stop Lamp Switch
- ABS Control Module
- Cruise Control Module
C0205 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.