C0045 on 2014-2019 Cadillac CTS: Causes and Fixes for the Left Rear Wheel Speed Fault

What's Unique About the 2014-2019 Cadillac CTS

For this generation of Cadillac CTS and many other GM vehicles built on the Alpha platform, the wheel speed sensor is an active sensor that reads a magnetic encoder ring integrated into the wheel hub and bearing assembly. This design makes the ring susceptible to collecting metallic brake dust and road debris. GM has issued multiple Technical Service Bulletins (TSBs) acknowledging that this debris accumulation is a primary cause for code C0045, often leading to a misdiagnosis of the sensor itself. The official recommendation is to inspect and clean this ring before considering any part replacement.

Symptoms You May Notice

• ABS warning light is on
• "Service StabiliTrak" message displayed on the dashboard
• "Service Traction Control" message displayed
• Cruise control is disabled
• In vehicles with electric power steering, a "Service Steering" message may appear with heavier steering feel at low speeds

Most Likely Causes

1. Metallic Debris on Wheel Hub Magnetic Encoder Ring 🔴 High Probability The magnetic encoder ring is part of the wheel hub assembly and its exposed nature makes it prone to collecting ferrous debris from brake wear and road grime. This is a well-documented issue covered by multiple versions of GM Technical Service Bulletin PIC5428.
   How to confirm: Remove the brake caliper and rotor to visually inspect the magnetic ring on the inboard side of the wheel hub. Look for a build-up of dark, metallic dust or larger debris stuck to the ring's surface.
   Typical fix: Clean the ring thoroughly with a soft nylon brush and a mild cleaner like brake cleaner or soap and water. Ensure it is completely dry before reassembly. This often resolves the code without any cost for parts.
   Est. part cost: $0
2. Damaged or Cracked Wheel Hub Magnetic Encoder Ring 🟡 Medium Probability The encoder ring is a somewhat delicate magnetic strip. Age, heat cycles, corrosion, or impact from road debris can cause it to crack, delaminate, or break apart, making it unreadable by the sensor.
   How to confirm: During visual inspection, look for physical damage to the brown magnetic ring on the hub, such as cracks, missing sections, or peeling. The ring may appear intact but have lost its magnetic properties in spots.
   Typical fix: The magnetic ring is not serviced separately. The entire wheel hub and bearing assembly must be replaced. 🎬 Watch this step-by-step Cadillac CTS rear wheel hub replacement guide
   Est. part cost: $150-$350
3. Failed Left Rear Wheel Speed Sensor ⚪ Low Probability → Shop ABS Wheel Speed Sensor While less common than hub issues on this platform, the sensor itself lives in a harsh environment and can fail from moisture intrusion, internal corrosion, or vibration over time.
   How to confirm: After confirming the hub ring is clean and intact, swap the left and right rear wheel speed sensors. If the code changes to C0050 (Right Rear), the sensor is faulty. If the code stays C0045, the problem is the hub or wiring.
   Typical fix: Replace the left rear wheel speed sensor. The sensor is typically held by one T30 Torx bolt and has a wire that routes up into the fender liner to a connector.
   Est. part cost: $30-$90
4. Damaged Wiring or Connector ⚪ Low Probability The wiring harness can be damaged by road debris, improper routing after previous repairs, or corrosion at the connector pins. The connector is located in the wheel well and can be susceptible to moisture.
   How to confirm: Visually inspect the entire length of the sensor's wiring harness from the hub to the main connector inside the wheel well. Look for chafing, breaks, or green/white corrosion on the connector pins. Use a multimeter to check for continuity and shorts between the sensor connector and the EBCM connector.
   Typical fix: Repair the damaged section of wire or replace the sensor pigtail/harness if the damage is near the connector.
   Est. part cost: $20-$50

Rare But Worth Checking

• Faulty Electronic Brake Control Module (EBCM): → Shop ABS Control Module This is very rare. All other possibilities, including the hub, sensor, and wiring, should be exhaustively ruled out before considering the EBCM as the cause.

Diagnosis Steps

1. Connect an OBD-II scanner capable of reading ABS codes to confirm C0045 is the active code. 🎬 Watch: How to diagnose and fix C0045 and C0050 codes Note any symptom bytes (e.g., 0F, 18, 5A) if your scanner supports it.
2. Safely raise and support the vehicle, then remove the left rear wheel.
3. Remove the brake caliper and brake rotor to gain access to the wheel hub assembly.
4. Visually inspect the magnetic encoder ring on the inboard side of the hub. Look for metallic debris, rust, cracks, or physical damage.
5. If debris is present, clean the ring with a soft brush and brake cleaner. Clear the code and test drive to see if the fault returns.
6. If the ring is clean and intact, inspect the wheel speed sensor and its wiring harness for any visible damage, chafing, or corrosion at the connector.
7. For a definitive diagnosis, swap the left and right rear wheel speed sensors. Clear the codes and drive the vehicle. If code C0050 appears, the sensor you moved is faulty. If C0045 returns, the problem lies with the hub or wiring on the left side.
8. If a scan tool with live data is available, monitor the output from the left rear wheel speed sensor while spinning the wheel by hand. Compare its reading to the other wheels. A reading of zero or one that is erratic confirms a fault at that corner.
9. If wiring is suspected, check for continuity on the two wires from the wheel speed sensor connector to the EBCM connector. Check for shorts to ground and shorts to power.

Parts You'll Likely Need

• Rear Wheel Hub and Bearing Assembly (OEM #19421348) — This is the most common part replaced for this code if cleaning the magnetic ring doesn't work, as the ring itself is integrated into the hub and is often the true point of failure due to damage or cracking.
  Trusted brands: ACDelco, Timken, MOOG, SKF
  OEM price range: $250-$350
  Aftermarket price range: $150-$250
• Rear Wheel Speed Sensor (OEM #19435260) — Replaced only if it's confirmed to be the point of failure, typically through swapping sensors side-to-side for diagnosis. The original part number 25866179 was superseded by 19435260.
  Trusted brands: ACDelco, Standard Motor Products (SMP), Delphi
  OEM price range: $60-$90
  Aftermarket price range: $30-$50

Related Codes That Often Appear With This One

• U0415 — This code, "Invalid Data Received From EBCM," may be set by the Power Steering Control Module. It is a normal default action when a wheel speed signal is lost, and it typically resolves itself once the C0045 fault is corrected.

Technical Service Bulletins (TSBs) & Recalls

• PIC5428G: Addresses ABS, StabiliTrak, and other warning lights with DTCs C0035, C0040, C0045, or C0050. It identifies the common cause as ferrous metallic debris on the wheel bearing's magnetic encoder ring and advises cleaning as the primary diagnostic step 🎬 See why debris on the encoder ring causes these faults before part replacement. This TSB applies to a wide range of GM vehicles, including the 2013-2014 ATS, a platform mate.
• 17-NA-047: This bulletin supersedes PIC5428G, carrying forward the same diagnostic advice for wheel speed sensor codes caused by debris on the hub's magnetic ring.

Platform-Specific Known Issues

• Owner Experience: Replaced Sensor, Hub was the Real Issue: A common story on forums involves an owner first replacing the C0045 code's associated wheel speed sensor, only for the 'Service StabiliTrak' light to return. After further diagnosis, often by swapping sensors side-to-side with no change in the code, they discover the magnetic ring on the hub is cracked or damaged. Replacing the entire wheel hub assembly finally resolves the issue.

Mechanic-Grade Diagnostic Values

• Active Wheel Speed Sensor Signal Current — expected: Switches between 7mA (Low) and 14mA (High) as the wheel rotates.. Failure: A signal that is stuck high, low, or is erratic indicates a fault in the sensor, ring, or wiring.
• Wheel Bearing Hub Assembly Runout — expected: Less than 0.005 inches (0.27 mm).. Failure: A measurement greater than 0.005 inches indicates excessive play in the bearing, which can cause an erratic signal. The hub should be replaced.

Hidden / Shadow Codes Worth Checking

• C0045 06: Low Voltage/Open Circuit. Points to an open wire, poor connection, or short to ground. (see via GM GDS2 or equivalent professional scan tool capable of reading symptom bytes.)
• C0045 0F: Signal Erratic. Often caused by debris on the magnetic encoder ring, a cracked ring, or excessive bearing play. (see via GM GDS2 or equivalent professional scan tool capable of reading symptom bytes.)
• C0045 18: Low Signal Amplitude / Missing Signal. Can be caused by debris on the magnetic encoder ring or a complete circuit failure. (see via GM GDS2 or equivalent professional scan tool capable of reading symptom bytes.)
• C0045 5A: Signal Plausibility Failure. The signal doesn't make sense compared to other wheels. Often caused by debris on the magnetic encoder ring. (see via GM GDS2 or equivalent professional scan tool capable of reading symptom bytes.)

Scan Tool Commands That Help

• GDS2 (GM Global Diagnostic System 2): Vehicle Diagnostic History / Module Diagnostics — Use the 'Module Diagnostics > EBCM > Data Display' function to view live wheel speed sensor data from all four wheels simultaneously. A failing left rear sensor will read 0 or have an erratic value compared to the others while the vehicle is moving slowly.
• GDS2 (GM Global Diagnostic System 2): Vehicle Build Modification (Workaround) — On 2014 models specifically, if GDS2 fails to communicate with the Electronic Brake Control Module (EBCM), there is a known software bug. The official workaround is to build the vehicle in the tool as a 2013 model year. This will allow communication and diagnosis of ABS codes.

Wiring & Ground Locations

• EBCM (Electronic Brake Control Module) — Located in the right rear corner of the engine compartment.. This module receives the signal from the left rear wheel speed sensor. All diagnostic wiring tests (continuity, short to ground/power) will terminate at this module's connector.
• G110 — In the engine compartment, near the ABS module (EBCM).. This is a primary ground point for the anti-lock brake system. A loose or corroded G110 ground can cause various ABS faults, including erratic behavior that could be misdiagnosed as a single sensor issue.
• Left Rear WSS Connector — Inside the rear of the driver's side fender liner. The harness routes from the sensor on the knuckle up into the liner.. This is the first point of disconnection for testing. It is exposed to moisture and road debris, making it a potential point of failure due to corrosion on the pins.
• EBCM Connector Pins (Left Rear) — At the 38-pin EBCM connector.. Wiring diagrams show specific pins for 'Lh rr wheel spd sens 12v ref' (power feed) and 'Lh rr wheel spd sens sig' (signal return). These are the specific pins to test for continuity back from the sensor connector.

Real Owner Repair Stories

• YouTube channel 'An_Auto _Addiction' (2012 Cadillac CTS 3.0L V6 (previous generation, but identical hub/sensor design)) — ABS, Traction Control, and StabiliTrak lights on. Codes C0045 and C0050 (both rear sensors erratic).
  ❌ Tried (didn't work) Initial diagnosis pointed to sensors, but since both failed simultaneously, the hubs were suspected.
  ✅ What actually fixed it Both rear wheel hub assemblies were replaced. Upon inspection, the magnetic encoder rings on the old hubs had physically broken apart and worn away, preventing the sensors from getting a reading.
• NHTSA ODI #11219167 — An owner reported an ABS stability code (C0045) where the left rear wheel speed sensor encoder ring was broken. The repair required replacing both the speed sensor and the rear hub assembly.

OEM Part Supersession History

• 25866179 → 19435260 — Part revision and optimization by GM.
• Varies (Original Hub) → 19421348 (GM), FW454 (ACDelco) — Service replacement part number for the rear wheel hub assembly.
  Heads up: Ensure the correct part is ordered for RWD vs AWD models if applicable, although many rear hubs are shared.

Model Year Variations Within This Range

• 2014: A software bug exists in the GM GDS2 scan tool that may prevent communication with the Electronic Brake Control Module (EBCM) on 2014 models. The official workaround is to select '2013' as the model year in the tool to establish a diagnostic session.

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• CUE Infotainment Screen Failure 🟠 Medium — Extremely common. The touchscreen's digitizer delaminates or fails, causing 'ghost touches' or unresponsiveness, often within 3-5 years of service. A class-action lawsuit was filed over this issue.
• 8-Speed (8L45/8L90) Transmission Shudder 🟠 Medium → Shop Transmission Assembly — A widespread issue where the torque converter causes a shudder or vibration at steady speeds, often described as driving over rumble strips. It affected many GM vehicles. (Ref: Multiple TSBs exist, including 18-NA-355, which recommend a specific fluid flush procedure with an updated Mobil 1 synthetic fluid.)
• Carbon Buildup on Intake Valves (Direct Injection Engines) 🟡 Low — Common to all direct-injection engines (2.0T LTG and 3.6L LGX). Over time (typically 50k+ miles), carbon deposits can build up on the intake valves, potentially causing rough idle or misfires. (Ref: TSB PIP5029C addresses misfires due to carbon buildup and recommends a chemical cleaning procedure.)
• Rear Differential Failure/Noise 🔴 High — Less common on standard models but a known weak point, especially on higher-performance V-Sport models. Can manifest as whining or grinding noises. (Ref: Recall 20V-038 (GM N192279370) was issued for certain 2014-2015 CTS V-Sport models for fracturing roll pins in the differential that could cause wheel lock-up.)
• Timing Chain Issues (2.0T LTG Engine) 🟠 Medium — While improved over prior GM engines, the 2.0T LTG can still experience timing chain stretch, especially if oil change intervals are extended or the engine is run low on oil.

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: A used wheel speed sensor from a reputable salvage yard with known low mileage can be a cost-effective replacement or a good tool for diagnosis (swapping side-to-side). A used wiring pigtail is also a viable option if the connector is in good condition.

Donor-vehicle mileage cap: roughly under 60000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• For a sensor, ensure the plastic housing is not cracked and the connector pins are clean and straight.
• For a wiring pigtail, inspect for any cuts, abrasions, or signs of previous repair. Ensure the connector lock is intact.
• Avoid parts from vehicles with heavy front-end or side collision damage near the wheel in question.

OEM-only on this vehicle (don't cheap out):

• While not strictly 'OEM-only', using a reputable brand for the wheel hub assembly is critical. The integrated magnetic ring is a precision component, and cheap, unverified aftermarket hubs are a common source of repeat failures.

Aftermarket brands forum-validated for this vehicle:

• Hub Assemblies: Timken, MOOG, SKF, ACDelco
• Sensors: ACDelco, Delphi, Standard Motor Products (SMP), NTK

Brands owners have reported issues with on this vehicle:

• Unnamed, 'white-box' wheel hub assemblies from online marketplaces. These often use low-quality bearings and improperly manufactured magnetic rings that fail prematurely or are dead-on-arrival.

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• C0050 — This is the code for the Right Rear wheel speed sensor; it often appears alongside C0045 if both rear hub rings are deteriorating or is used for diagnostic swapping.
• C0035 — Left Front wheel speed sensor code; identified in TSB PIC5428G as sharing the same root cause of metallic debris on the encoder ring.
• C0040 — Right Front wheel speed sensor code; identified in TSB PIC5428G as sharing the same root cause of metallic debris on the encoder ring.

Frequently Asked Questions