Chassis, generic

C0235 Wheel Speed Sensor Signal Erratic

Check engine lightUsually off
EmissionsNot relevant
Drive cycleRequired
Limp modePossible

C0235 does not show up in the publicly available J2012 lists. GM's bulletin PIP5094 names the number among chassis codes for cars and light trucks up to 2014, and AA1Car's GM-based ABS table renders it as Rear Wheel Speed Signal Circuit Open; an erratic-signal meaning is not documented by any maker. Taken by its title, the code concerns a speed signal that jumps or briefly drops out while the wheel turns steadily. HELLA's workshop guide names broken wires, internal shorts, heavy dirt and a growing air gap as the usual reasons, with pseudo control interventions or locking wheels as symptoms, and recommends comparing the wheel signals in live data and on a scope. Bosch's Hall sensors turn the encoder field into square current pulses, so a loose plug shows as missing pulses.

Likely causes

Intermittent wire break or loose connector, often at moving harness sections
Dirt, rust or metal debris on the sensor, enlarged air gap
Wheel bearing play letting the encoder wobble

Symptoms

  • ABS lamp comes and goes
  • Pulsing pedal or ABS intervention at low speed without reason

Repair estimate

DifficultyMediumDIY possible
Parts and labour€30–300
Time0.5–2 h

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

Parts involved

wheel speed sensortone ringabs control module

Related codes

C0234C0237C0245

References: static.nhtsa.gov, aa1car.com, hella.com, bosch-mobility.com.