C0401 code meaning
Traction Control Switch Circuit
What C0401 means
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.
C0401 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 1 hours
- Clears after repairWhen cleared with a scanner
Symptoms of C0401
- Traction or stability control cannot be switched off or on
- TCS OFF or ESP OFF lamp lit permanently
Common causes of C0401
- PossibleButton stuck pressed or contacts dirty
- PossibleOpen or grounded lead between button and brake module
- Less likelyLiquid spilled into the switch panel
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Tcs switchDashboard wiringABS control module
What each part of C0401 means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 01 | The exact fault in that area. |
What to do next
- Note C0401 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about C0401
What does C0401 mean?
C0401 means "Traction Control Switch Circuit". There is no public evidence that any maker uses C0401. It is a generic code, so it means the same on every make.
Is it safe to drive with C0401?
C0401 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will C0401 fail an emissions test?
C0401 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is C0401 to fix?
Difficulty: easy. A typical repair takes 0.3 to 1 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will C0401 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.