C0050 Code: Right Rear Wheel Speed Sensor — Causes & Fix

Drashco
Mechanic working on a truck wheel in garage — C0050 right rear wheel speed sensor diagnosis
Photo: Gustavo Fring / Pexels

C0050 means: Right Rear Wheel Speed Sensor Circuit — the EBCM lost signal from the rear-right wheel speed sensor.
Most common fix: 65% sensor replacement ($25–$80). 20% wiring damage near rear axle. 10% tone ring corrosion. 5% other.
Time: 30–45 minutes (rear sensors slightly harder to access than front).

C0050 is the rear-right counterpart of C0035, C0040, and C0045. Same fault mechanism, opposite wheel from C0045. Together with C0035, C0040, and C0045 it completes the wheel-speed sensor family.

In this guide:

What C0050 Means

C0050 reads as "Right Rear Wheel Speed Sensor Circuit". The EBCM expected a clean square-wave signal from the rear-right wheel sensor and got nothing, erratic, or out-of-range data. ABS, traction control, StabiliTrak, and (on equipped models) hill-start assist all disable as a safety fallback.

The rear sensor lives near the rear hub or differential, with a tone ring on the rotating axle. On rear-wheel-drive and 4WD vehicles, the sensor may be on the differential rather than at the wheel hub.

Symptoms

  • ABS warning light on solid
  • Traction Control / StabiliTrak light on
  • "Service Brake System" or "Service ABS" message on the DIC
  • Hill-start assist disabled on cars equipped
  • Cruise control may not engage
  • Engine runs normally

Causes Ranked by Frequency

1. Wheel-speed sensor failure — 65% of cases

Internal coil break. Less common than front sensors because rear sensors run cooler.

2. Damaged sensor wiring near rear axle — 20% of cases

The pigtail runs along the rear axle and rear suspension components. Damaged by stones, road debris, sometimes by improper tire-shop work that pulls the wire during wheel removal.

3. Tone ring corrosion — 10% of cases

Tone ring on rear hub corrodes from road salt, especially on cars in salt-belt states. Missing teeth = missing pulses.

4. EBCM internal fault — 5% of cases

Rare. Confirm sensor + wiring + tone ring before suspecting EBCM.

Step-by-Step Diagnosis

  1. Lift the vehicle and remove the rear-right wheel.
  2. Locate the sensor on the rear knuckle or backing plate near the brake drum/rotor. Two-wire (passive) or three-wire (active) connector with single bolt.
  3. Trace the wiring from sensor to chassis connector — usually runs up to the wheel-well or trunk floor.
  4. Inspect tone ring on the hub flange — sometimes located inside the bearing, sometimes outside on the axle stub.
  5. Resistance test (passive): 1,000–2,500 ohms. Open = dead.
  6. Voltage test (passive): spin wheel by hand, measure AC voltage across pins. Should be 0.1–1V.
  7. Cross-test: swap with the rear-left sensor. If code follows = sensor bad. If stays = wiring or tone ring.

Replacing the Rear Sensor

  1. Disconnect negative battery, wait 60 seconds.
  2. Lift vehicle, remove rear-right wheel.
  3. Remove brake drum or caliper (some sensors require this; others are accessible without).
  4. Remove sensor mounting bolt (10mm or 13mm).
  5. Twist and pull sensor — penetrating oil if stuck.
  6. Trace wiring back to chassis connector. Unplug.
  7. Install new sensor with anti-seize on the mounting hole. Route wiring identical to old.
  8. Plug into chassis connector. Reinstall brake components, wheel.
  9. Reconnect battery. Clear codes. Drive 20 minutes.

Cost: $25–$80 sensor. Shop labor: $120–$220 (rear is slightly more than front). DIY: 30–45 minutes.

Frequently Asked Questions

What's the difference between C0050 and C0045?

C0050 = Right Rear Wheel Speed Sensor. C0045 = Left Rear Wheel Speed Sensor. Same fault mechanism, opposite side. The reset and replacement steps are identical, just on the opposite wheel.

I have C0045 + C0050 together — what does that mean?

Both rear sensors out simultaneously usually points to: (1) shared wiring damage in the harness section that splits to both rear wheels (rodent damage is common), (2) connector corrosion where the rear harness joins the chassis side, or (3) failed EBCM rear channel.

Can I drive with C0050 active?

Yes at normal speeds, short distances. Base brakes work. You lose ABS, traction control, StabiliTrak, hill-start assist. Avoid ice and heavy rain.

Does C0050 affect the parking brake?

Not directly — the parking brake is a separate mechanical system. But on cars with electronic parking brake (EPB), some manufacturers disable EPB engagement when wheel-speed sensors are faulty for safety reasons.

Will swapping the rear-right sensor with the rear-left help diagnose?

Yes — best quick test. If the code follows the sensor (now reads as C0045), the sensor itself is bad. If the code stays at the right-rear (C0050 persists), the wiring or tone ring at the right-rear is the issue.

How do I know if my sensor is "active" or "passive"?

Passive = 2 wires, AC voltage as wheel spins. Active = 3 wires (powered), digital square wave. Modern (2008+) GM, Ford, most Europeans = active. Older = passive. Resistance test only works on passive sensors.

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