C0401Traction Control Switch Circuit
- Generic OBD-II code · Chassis
- How the car detects it
- There is no public evidence that any maker uses C0401. The code is missing from the publicly available J2012 lists and from GM's PIP5094; the only NHTSA index hit is a BMW program number. The description is limited to the switch itself. On the 2004 Saab 9-5 a spring-loaded dash button beside the steering wheel turns ESP and TCS off together; it grounds a supply from the brake module, works for switching off only below 60 km/h, and after more than ten seconds pressed forces the system on until the next ignition cycle without storing a code. FMVSS 126 allows such an off control but demands that stability control come back in its default mode at every new ignition cycle. A shorted or open button circuit leaves the driver unable to change the mode.
- What you may notice
- Traction or stability control cannot be switched off or on
- TCS OFF or ESP OFF lamp lit permanently
- Likely causes
- PossibleButton stuck pressed or contacts dirty
- PossibleOpen or grounded lead between button and brake module
- RareLiquid spilled into the switch panel
- Repair
- Easy · Often possible to do yourself.Typical cost: €20 – €200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.