C0050 (C0050-18, C0050-0F) on 2010-2016 Buick LaCrosse: Right Rear Wheel Speed Sensor Fault Explained

What's Unique About the 2010-2016 Buick LACROSSE

The 2010-2016 Buick LaCrosse, along with many other GM vehicles from this era, is particularly susceptible to this code due to the design of its wheel hub assembly. As documented by GM in TSB PIC5428G, the sensor reads a magnetized nitrile rubber ring integrated into the hub. This open design can attract and accumulate metallic debris, often described as 'fuzz'. This debris interrupts the sensor's reading, causing a fault code even if the sensor and hub are mechanically sound. Furthermore, this magnetic ring can become brittle, crack, or have entire chunks break off, causing a permanent signal loss. This makes a visual inspection and cleaning of the hub face a critical first diagnostic step before replacing any parts.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• ABS light illuminated on the dashboard
• Traction Control (TCS) or StabiliTrak light on
• "Service StabiliTrak" or "Service Brake Assist" message in the driver information center
• ABS system fails to activate during hard braking (wheels may lock up)
• Traction control does not engage on slippery surfaces
• On some models, a "Service Steering" message may appear and steering may feel heavier at low speeds as a default action.

Most Likely Causes

1. Debris on Wheel Hub Magnetic Encoder Ring 🔴 High Probability GM Technical Service Bulletin PIC5428G specifically calls out this issue for the 2010-2016 LaCrosse. The design of the open magnetic ring on the hub assembly makes it prone to collecting metallic 'fuzz' that disrupts the sensor signal.
   How to confirm: Remove the right rear wheel and wheel speed sensor. Visually inspect the inboard face of the hub for a build-up of metallic particles on the black magnetic ring. A scan tool may show an erratic signal (C0050-0F).
   Typical fix: Thoroughly clean the debris from the magnetic ring using a soft nylon brush or cloth and compressed air. TSBs explicitly warn not to use a magnet or harsh tools for cleaning, as this can damage the encoder. If the code returns, the hub assembly must be replaced. 🎬 See this step-by-step rear wheel bearing replacement for FWD models.
   Est. part cost: $0
2. Failed Right Rear Wheel Hub and Bearing Assembly (Damaged Magnetic Ring) 🟡 Medium Probability The wheel speed sensor's magnetic encoder ring is integrated into the hub assembly. Over time, this ring can become brittle, crack, or have sections break off, causing a permanent loss of signal. This is a very common failure point documented by many owners.
   How to confirm: After cleaning the hub, the code persists. A scan tool may show low or no signal (C0050-18). Visual inspection after removing the sensor may reveal missing chunks of the black magnetic ring. One owner noted his was 'about 85% gone'.
   Typical fix: Replace the entire right rear wheel hub and bearing assembly. The magnetic ring is not serviced separately.
   Est. part cost: $100-$280
3. Damaged Wiring or Connector ⚪ Low Probability
   How to confirm: Visually inspect the wiring harness leading to the right rear wheel speed sensor for any signs of chafing, breaks, or corrosion, from the wheel well back to the main harness. Check the connector pins for corrosion or a loose fit. A multimeter can be used to check for continuity from the EBCM connector to the sensor connector.
   Typical fix: Repair the damaged section of wire or replace the pigtail connector.
   Est. part cost: $20-$50

Rare But Worth Checking

• Failed Electronic Brake Control Module (EBCM): This is extremely rare and should only be considered after the hub assembly and wiring have been definitively ruled out. This is an expensive last resort and typically would present with multiple other codes, not just a single wheel speed sensor fault.

Diagnosis Steps

1. Connect a scan tool capable of reading ABS/Chassis codes to verify C0050 is active or in history. Note any symptom bytes like -18, -0F, or -5A.
2. Use the scan tool to view live data from all four wheel speed sensors. Drive the vehicle slowly (above 4 mph) and observe if the right rear sensor reads 0 MPH or has an erratic signal compared to the others.
3. Safely raise and support the rear of the vehicle and remove the right rear wheel.
4. Inspect the wiring harness leading to the hub for any visible damage, chafing, or corrosion.
5. Unbolt (typically a 10mm or T30 Torx bolt) and remove the wheel speed sensor from the knuckle.
6. Carefully inspect the black magnetic encoder ring on the inboard side of the hub assembly. Shine a light into the hole and slowly rotate the hub. Look for a build-up of metallic debris, rust, or missing/cracked sections of the ring.
🎬 Watch: How to inspect and clean the rear magnetic reluctor ring.
7. If debris is present, clean it off with a soft nylon brush and compressed air. Reassemble and test drive to see if the code is resolved.
8. If the ring is clean but visibly damaged (cracked, missing pieces), the hub assembly must be replaced.
9. If the ring looks good and is clean, but the code persists (especially a C0050-18), the hub assembly's internal magnetic ring has likely failed. Proceed with replacing the wheel hub and bearing assembly.

Parts You'll Likely Need

• Right Rear Wheel Hub and Bearing Assembly (OEM #19435272) — This assembly contains the integrated magnetic encoder ring that fails or collects debris, causing code C0050. The sensor and ring are not serviced separately, so the entire hub must be replaced if cleaning does not resolve the issue or the ring is damaged.
  Trusted brands: ACDelco (OEM), Timken, MOOG, SKF, FAG, TRQ
  OEM price range: $180-$280
  Aftermarket price range: $100-$180
• ABS Wheel Speed Sensor Wiring Harness Pigtail — If the diagnostic process points to a fault in the connector or the wiring immediately attached to it, replacing the pigtail is often easier than repairing individual wires.
  Trusted brands: Dorman, Standard Motor Products (SMP)
  OEM price range: $50-$80
  Aftermarket price range: $20-$50

Related Codes That Often Appear With This One

• C0045 — This is the code for the Left Rear Wheel Speed Sensor. Seeing both C0045 and C0050 could indicate a shared wiring problem or similar wear/debris issues on both rear hubs.
• C0800 — As noted in TSB PIC5837, this code for 'System Voltage Low' can appear alongside C0050. The bulletin advises diagnosing the wheel speed sensor code first, as resolving it often clears the C0800.
• U0415 — TSB PIC5428G notes this code ('Invalid Data Received From EBCM') may be set in the Power Steering Control Module, causing a 'Service Steering' message. This is a normal default action when a wheel speed signal is lost, and it should clear once the C0050 fault is repaired.

Technical Service Bulletins (TSBs) & Recalls

• PIC5428G (and its successors like 17-NA-047): This is the key document for this issue. It advises that codes C0035-C0050 with symptom bytes 18, 5A, or 0F are often caused by debris on the wheel bearing's magnetic encoder ring. It provides a cleaning procedure, warns against using magnets for cleaning, and lists dozens of affected GM models, confirming this is a widespread design issue.
• PIC5837: Notes that a 'Service Stability' message with code C0800 can accompany C0050, and instructs technicians to diagnose the C0050 fault first.

Platform-Specific Known Issues

• As per GM TSB PIC5428G and its successors, the 2010-2016 LaCrosse is highly prone to metallic debris accumulating on the wheel bearing's magnetic encoder ring, leading to C0050 and other wheel speed sensor codes. This issue is not unique to the LaCrosse and affects a wide range of GM vehicles from the era, including the Regal, Impala, XTS, Equinox, and Traverse.
• A common point of failure is the physical degradation of the magnetic ring itself, where it cracks or chunks of it break away entirely, which is a more definitive failure than simple debris.

Mechanic-Grade Diagnostic Values

• Wheel Speed Sensor Supply Voltage — expected: Greater than 11V between the ignition circuit terminal (Pin 1 at sensor connector) and ground with ignition ON.. Failure: Voltage below 11V indicates an issue with the wiring or the EBCM.
• Wheel Speed Sensor Signal (Active Sensor) — expected: The sensor is an active, 2-wire magneto-resistive type. It produces a digital square wave, not an AC sine wave. With a lab scope, the signal should switch between a low state (approx. 0.7V or 7mA) and a high state (approx. 1.4V or 14mA) as the wheel turns.. Failure: A flat-line signal, a signal that does not switch, or an erratic/noisy pattern indicates a failed sensor, damaged encoder ring, or wiring issue.
• EBCM 12V Driver Pulse Check — expected: When the ignition is first cycled ON, the EBCM sends a brief 12V pulse to the sensor circuit to check for integrity. This can be captured with an oscilloscope.. Failure: Absence of this pulse could point to an EBCM issue, but be aware the EBCM will disable this driver if a fault is already stored.

Hidden / Shadow Codes Worth Checking

• C0050 06: Right Rear Wheel Speed Sensor Circuit Low Voltage/Open. This points toward a short to ground or an open/high resistance in the sensor's power feed circuit. (see via Professional scan tools like the GM GDS2 or Tech2 will display these two-digit symptom bytes.)
• C0050 0F: Right Rear Wheel Speed Sensor Circuit Signal Erratic. This often corresponds to debris on the magnetic encoder ring or a cracked ring causing an inconsistent signal. (see via Professional scan tools like the GM GDS2 or Tech2.)
• C0050 18: Right Rear Wheel Speed Sensor Circuit Low Signal Amplitude. This can mean a missing signal or a very weak one, often caused by a large air gap or a severely damaged/missing encoder ring. (see via Professional scan tools like the GM GDS2 or Tech2.)
• C0050 5A: Right Rear Wheel Speed Sensor Circuit Not Plausible. The EBCM is receiving a signal, but it doesn't make sense compared to the other wheel speed sensors (e.g., showing 5 MPH when others show 50 MPH). (see via Professional scan tools like the GM GDS2 or Tech2.)

Scan Tool Commands That Help

• GM GDS2 / Tech2: EBCM Data Display > Wheel Speed Sensor Data — This is the primary diagnostic step. Use this to view the live data stream from all four wheel speed sensors simultaneously while driving. A faulty right rear sensor will read 0, lag behind, or show erratic jumps compared to the other three.
• GM GDS2 / Tech2: Clear All DTCs — After performing a repair (like cleaning the hub or replacing a part), use this function to clear the C0050 code. Note that on these active systems, the EBCM may disable the 12V supply to the sensor when a code is set. Clearing the code is necessary to re-energize the circuit for testing.

Wiring & Ground Locations

• EBCM Main Ground — The Electronic Brake Control Module (EBCM) is located on the hydraulic modulator assembly in the engine bay. Its primary chassis ground is typically a short black wire bolted to the frame rail or inner fender very close to the module itself.. A poor EBCM ground can cause a host of erratic electronic issues, including false sensor codes and communication problems. While not a common cause for a single wheel speed sensor code, it should be checked for tightness and corrosion if multiple, seemingly unrelated ABS codes are present.
• RR WSS Harness Connector — The harness connector for the right rear wheel speed sensor is located in the right rear wheel well, typically clipped to the subframe or body. The sensor wire runs from the back of the hub assembly to this connection point.. This connector is a common point for corrosion or loose pins due to its exposure to the elements. It's the first place to check for wiring issues after the sensor itself.
• EBCM Connector Pins (RR WSS) — At the main harness connector for the EBCM. The Right Rear Wheel Speed Sensor signal wire is a Dark Green/White wire, and the ignition voltage feed is a Yellow/Light Blue wire.. For advanced diagnostics, a technician would test for continuity and shorts on these specific wires between the EBCM connector and the sensor connector in the wheel well to rule out a harness break.

Real Owner Repair Stories

• Reddit user on r/MechanicAdvice (2015 Buick LaCrosse) — ABS light came on after curbing the passenger rear wheel, followed by driving on a rough dirt road. Code C0050-18 was present.
  ❌ Tried (didn't work) Initial query was about replacing the sensor first.
  ✅ What actually fixed it The user later updated that the problem was fixed by replacing the entire wheel hub assembly because the magnetic 'tone ring was whooped out'. They also recommended replacing the ABS sensor at the same time, as reusing the old one is 'mostly impossible' without damaging it during removal.
• YouTube channel 'Matt Cross' (2012 Buick LaCrosse) — ABS and Stabilitrak lights on with code C0050.
  ❌ Tried (didn't work) The video focuses on direct diagnosis rather than trial-and-error parts replacement.
  ✅ What actually fixed it After removing the sensor for inspection, a visual check of the magnetic reluctor ring on the back of the hub showed a large chunk was missing. The definitive fix was the replacement of the right rear wheel hub and bearing assembly.

Model Year Variations Within This Range

• 2012-2016: Models with the eAssist (mild hybrid) system have a different Battery Energy Control Module (BECM) and Generator Control Module (GCM) that are integrated with the vehicle's stability and braking systems. While the C0050 fault remains primarily a hub/sensor issue, diagnostics on eAssist models must ensure the hybrid system is not causing related electrical interference, though this is not a commonly reported cause.