Chassis, generic

C0003 TCS Control Channel B Valve 1

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

C0003 is the counterpart of C0001 in channel B, the second brake circuit of the modulator. A pump patent for such units shows the layout plainly: two normally open isolation valves and two normally closed priming valves, one of each per circuit, operated by the control unit alongside the apply and release valves when traction control intervenes. Valve 1 of channel B therefore matches the first valve of the other circuit; the published sources do not fix which function carries the number. A coil open or short, a current outside the expected window or a pressure that fails to follow the command sets the code. Traction and stability control are disabled and the warning lamp lights, while ordinary braking is unaffected. 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 b1

Related codes

C0001C0002C0004

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