Chassis, generic

C0004 TCS Control Channel B Valve 2

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

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.

Likely causes

Solenoid coil open or shorted
Corroded or chafed wiring to the modulator
Internal hydraulic modulator fault

Symptoms

  • ABS warning lamp on
  • Traction and stability control disabled
  • Normal braking retained without ABS

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€300–1,600
Time1.5–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

tcs valve b2

Related codes

C0001C0002C0003

References: rosap.ntl.bts.gov, patents.google.com, en.wikipedia.org.