C0161
ABS/TCS Brake Switch Circuit
The ABS or traction control module has detected an implausible signal from the brake light switch. The switch tells the module whether the driver is braking and is used to inhibit traction control during braking.
- 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.
- Brake light switch failed or misadjustedCommon
- Wiring or connector faultPossible
Parts involved
- Brake Light Switch
- ABS Control Module
- Tcs Control Module
C0161 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.