C0401
Traction Control Switch Circuit
The TCS on/off switch reports an implausible state.
- 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.
- Switch failedCommon
- Wiring shortedPossible
Parts involved
- Tcs Switch
- Dashboard Wiring
C0401 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.