Chassis, generic

C0030 Left Front Tone Wheel

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

Covers the left front tone wheel (reluctor or encoder ring) that the wheel speed sensor reads to measure rotation. This is a signal-plausibility code rather than a sensor circuit fault: the module sees an erratic, noisy or intermittent speed signal consistent with a damaged, contaminated or loose tone ring rather than a sensor electrical failure. Volvo documents BCM-C0030 on the S80 together with a grinding noise at the wheel hub when the hub has shifted within the steering knuckle. A fault disables ABS, traction and stability control and lights the ABS warning lamp while base braking remains.

Likely causes

Damaged or contaminated tone ring
Loose or displaced hub bearing
Excessive sensor-to-ring air gap

Symptoms

  • ABS warning lamp on
  • ABS and stability control disabled
  • Grinding noise from wheel hub

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€100–700
Time0.8–2.5 h

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

Parts involved

lf tone wheel

Related codes

C0031C0033C0036

References: static.nhtsa.gov, en.wikipedia.org.