C0004 code meaning
TCS Control Channel B Valve 2
What C0004 means
C0004 completes the set with the second traction control valve of channel B. During an intervention the module closes the isolation valve and opens the priming valve of the circuit concerned so the pump can supply pressure to a wheel that is spinning; afterwards both return to rest so the driver's pedal again acts through the master cylinder. A valve that sticks or a coil that fails can therefore leave the pump without supply or keep the circuit isolated from the pedal, which is why the module reacts at once. It sets the code for an electrical fault or an implausible pressure response, switches off traction and stability control and lights the warning lamp. Base braking stays available. No manufacturer documents this code publicly.
C0004 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1.5 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of C0004
- ABS warning lamp on
- Traction and stability control disabled
- Normal braking retained without ABS
Common causes of C0004
- Most likelySolenoid coil open or shorted
- PossibleCorroded or chafed wiring to the modulator
- Less likelyInternal hydraulic modulator fault
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Tcs valve b2
What each part of C0004 means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 04 | The exact fault in that area. |
What to do next
- Note C0004 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 C0004
What does C0004 mean?
C0004 means "TCS Control Channel B Valve 2". C0004 completes the set with the second traction control valve of channel B. It is a generic code, so it means the same on every make.
Is it safe to drive with C0004?
Drive gently and only to a workshop. With C0004 the car can go into limp mode (reduced power) to protect itself.
Will C0004 fail an emissions test?
C0004 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 C0004 to fix?
Difficulty: workshop only. A typical repair takes 1.5 to 4 hours of work. This is a job for a workshop.
Will C0004 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.