Chassis, generic

C0039 Right Rear Tone Wheel

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

Covers the right rear tone wheel (reluctor or encoder ring) read by the right rear wheel speed sensor, completing the four-corner tone-wheel set with C0030, C0033 and C0036. It is a signal-plausibility code set when the module sees an erratic, noisy or intermittent rear speed signal consistent with a damaged, contaminated or loose tone ring rather than a sensor circuit failure. Ford documents the right rear sensor group including this corner on 2021 Bronco and Ranger vehicles with an illuminated ABS warning. A fault disables ABS, traction and stability control and lights the ABS warning lamp while base braking remains; electronic brake-force distribution is affected where it uses the rear sensors.

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

rr tone wheel

Related codes

C003AC0036C0033

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