C0045 on 2007-2014 Chevrolet Silverado: Left Rear Wheel Speed Sensor Circuit Fixes

What's Unique About the 2007-2014 Chevrolet Silverado

On the GMT900 platform, which includes the 2007-2014 Silverado, the rear wheel speed sensors are individual components that can be replaced separately from the wheel hub assembly. This is different from many other vehicles where the sensor is integrated into the hub. This design often makes the repair cheaper and simpler, as the failure is frequently just the sensor or its exposed wiring harness, not the entire hub. The front sensors on these trucks, however, are integrated into the hub assembly.

Generation note: This range covers the second generation (GMT900) of the Silverado, which ran from 2007-2013. The 2014 model year was an overlap, with the GMT900 sold as the 'Silverado HD' and the new K2XX generation also being introduced. The information here primarily applies to the GMT900 trucks, which are the vast majority within this year range.

Symptoms You May Notice

• ABS warning light is on
• Stabilitrak / Traction Control warning light is on
• "Service Stabilitrak" or "Service Traction Control" message on the driver information center
• ABS and traction control systems are disabled
🎬 Watch: Understanding the causes and fixes for the C0045 code
• Cruise control is disabled
• "Service Trailer Brake" message may appear

Most Likely Causes

1. Faulty Left Rear Wheel Speed Sensor 🔴 High Probability The sensor is exposed to road debris, moisture, and heat, leading to eventual failure. It is a common wear item, with many owners reporting failure after 100,000 miles. Forum users strongly recommend using genuine GM/ACDelco parts, as aftermarket sensors have a high rate of premature failure.
   How to confirm: Use a scan tool to monitor live data from the left rear wheel speed sensor while driving. If the reading is erratic, zero, or doesn't match the other wheels, the sensor is likely bad. You can also test the sensor's internal resistance with a multimeter; a good passive sensor should typically read between 800 and 2000 Ohms. An 'OL' or '0' reading indicates a bad sensor. Swapping the left and right rear sensors (if the harness length allows) and seeing if the code changes to C0050 is another effective diagnostic step.
   Typical fix: Replace the left rear wheel speed sensor. It is held in by a single bolt (typically a T30 Torx or 8mm/10mm hex head) on the rear axle housing.
   Est. part cost: $40-$80
2. Damaged Wiring or Connector 🔴 High Probability The wiring harness runs along the frame and axle, where it is vulnerable to being snagged, stretched, or corroded. A GM TSB for a similar platform (PIT4648D) notes that the harness can be misrouted, causing wires to break internally during suspension travel. Owners frequently find chafed or broken wires about 12 inches from the sensor plug or where the harness is clipped to the frame above the rear axle. The main chassis connector (X411) on the left frame rail is also a common spot for corrosion.
   How to confirm: Visually inspect the entire length of the wiring harness from the sensor to where it connects to the main loom on the frame. Pay close attention to areas where it flexes or is secured by clips. Look for chafing, breaks, or corrosion in the connector pins. Perform a continuity test on the wires between the sensor connector and the EBCM connector to find hidden breaks.
   Typical fix: Repair the broken section of wire using solder and heat-shrink tubing or replace the pigtail connector. The Dorman 970-041 is an available pigtail, though it's often listed for the front and may require modification.
   Est. part cost: $15-$40
3. Debris on Magnetic Encoder Ring or Sensor Tip 🟡 Medium Probability The rear axle can accumulate metallic shavings from normal gear wear. These particles can stick to the magnetic tip of the sensor or the encoder ring (reluctor ring) on the axle shaft, disrupting the signal. This is especially common on trucks used for towing or heavy hauling.
   How to confirm: Remove the wheel speed sensor and inspect its tip for a collection of metallic 'fuzz'. Inspect the encoder ring inside the axle housing through the sensor hole for contamination or damage. A clean Q-tip can be used to wipe the ring and check for debris.
   Typical fix: Clean the metallic debris from the sensor tip and the encoder ring. A full fix may require removing the axle shaft to clean the ring properly and changing the differential fluid to remove suspended particles.
   Est. part cost: $0-$20 (for brake cleaner and a rag)

Rare But Worth Checking

• Damaged Encoder Ring (Reluctor Ring): The ring on the axle shaft that the sensor reads can become cracked, damaged, or lose its magnetic properties, causing an erratic signal. This is less common than sensor or wiring failure but is a known issue. If multiple aftermarket sensors fail to fix the code, the ring is a strong suspect. Replacement requires removing the axle shaft.
• Faulty Electronic Brake Control Module (EBCM): While possible, EBCM failure is rare. It should only be considered after all other possibilities (sensor, wiring, encoder ring) have been exhaustively ruled out. An EBCM failure usually triggers multiple sensor codes or communication errors, not just a single one. Checking for a solid ground connection at the EBCM (often G103 or G300 on the frame rail) is a wise final step before condemning the module.

Diagnosis Steps

1. Connect a professional scan tool capable of reading ABS codes and live data.
2. Confirm C0045 is the active or stored code. Check for any specific sub-codes (e.g., 0F, 5A, 06).
3. Observe the live data stream for the 'Left Rear Wheel Speed' while driving above 5 MPH. Compare its reading to the other three wheels. If it reads 0 mph, is erratic, or doesn't match, proceed with physical inspection.
4. Raise and safely support the rear of the vehicle.
5. Visually inspect the wheel speed sensor wiring harness from the sensor on the axle tube up to the main connector (X411) on the frame rail. Look for any signs of damage, chafing, melting, or corrosion, paying special attention to harness clips and points of flex.
6. Disconnect the sensor and inspect the connector pins for corrosion or damage.
7. Test the sensor. With a multimeter set to Ohms, check the resistance across the two pins on the sensor itself. A reading between 800-2000 Ohms is typical for a good sensor. Set the meter to AC Volts, reconnect the sensor, and spin the wheel by hand; you should see a small AC voltage that increases with speed.
8. Remove the single T30 Torx or 8mm/10mm hex bolt holding the sensor in place and pull the sensor out of the axle housing. 🎬 Watch: A helpful guide to removing and replacing the ABS sensor It may be stuck; gentle twisting can help.
9. Inspect the magnetic tip of the sensor for metallic debris. Clean if necessary. Also, inspect the encoder ring inside the housing for visible damage or debris.
10. If the sensor tests bad or is suspect, replace it, preferably with an OEM/ACDelco part.
11. If a new sensor does not fix the issue, perform a continuity and short-to-ground test on the harness wires from the sensor pigtail to the EBCM connector to rule out a hidden wire break.

Parts You'll Likely Need

• Rear ABS Wheel Speed Sensor (OEM #20938122) — This is the most common part to fail for this code due to its exposed location and electronic nature. This part number supersedes older numbers 15121067 and 20763147.
  Trusted brands: ACDelco (GM OE), Delphi, Dorman
  OEM price range: $60-$90
  Aftermarket price range: $30-$60
• Rear ABS Wheel Speed Sensor Harness Connector (Pigtail) — If the wiring is damaged right at the connector, replacing the pigtail is the standard repair. Dorman 970-041 is a commonly available harness, but it is often listed for front applications and may require wiring modification.
  Trusted brands: ACDelco, Dorman
  OEM price range: $25-$40
  Aftermarket price range: $15-$30

Related Codes That Often Appear With This One

• C0050 — This code is for the Right Rear Wheel Speed Sensor. It's common to see C0045 and C0050 together if there's a wiring issue common to both rear sensors (like corrosion in the main X411 connector) or if both sensors fail around the same time due to age.

Technical Service Bulletins (TSBs) & Recalls

• PIE0456A: An engineering information bulletin for 'Service Stabilitrak/ABS' lights with DTC C0045 or C0050 on 2018 HD models. GM was investigating harness and terminal issues, highlighting it as a known problem area. The bulletin is now closed.
• PIT4648D: A preliminary information bulletin for other GM trucks that specifically mentions the rear wheel speed sensor harness being misrouted from the factory, causing it to stretch and break wires internally during normal suspension movement.
• Bulletin #PIE0533A: This manufacturer bulletin notes that engineering information was gathered regarding wheel speed sensors becoming inoperative with DTCs including C0035, C0040, C0045, and C0055.
• Bulletin #PIT5499B: A manufacturer service bulletin notes that technicians may find C0045 along with a "Service Trailer Brake" message, and should inspect the Electronic Brake Control Module (EBCM) connector for water intrusion.
• Bulletin #PIT5427B: This bulletin for related GM platforms indicates that C0045 can be stored alongside other chassis codes and recommends that technicians inspect the X411 connector for damage.

Platform-Specific Known Issues

• Wiring harness chafing is very common. Owners report the harness rubbing through on the frame rail, near the shock absorber mounts, or at the plastic clips holding it in place.
• Poor quality of aftermarket sensors is a frequent complaint. Many DIY repairs fail because the replacement non-OEM sensor is also bad, leading to a frustrating diagnostic loop.
• The main chassis harness connector (X411), located on the left frame rail above the rear axle, is susceptible to water intrusion and pin corrosion, which can cause this code intermittently, especially in wet weather.

Mechanic-Grade Diagnostic Values

• Wheel Speed Sensor Resistance — expected: 850 - 1350 Ohms. Failure: A reading of 'OL' (open loop) or 0 Ohms indicates a failed sensor.
• Wheel Speed Sensor AC Voltage Output — expected: Greater than 100mV AC while spinning the wheel by hand.. Failure: No voltage or very low voltage suggests a bad sensor or a problem with the reluctor ring.
• EBCM Bias Voltage at Sensor Connector — expected: ~4.8 Volts DC (with sensor disconnected, ignition on). Failure: No voltage indicates a wiring problem between the EBCM and the sensor connector. Wiggling the harness while monitoring this voltage can reveal intermittent breaks.

Hidden / Shadow Codes Worth Checking

• C0045 06: Left Rear Wheel Speed Sensor Circuit Low Voltage/Open. This symptom byte points specifically to an open wire, a poor connection, or a short to ground in the circuit. (see via GM Tech2, GDS2, or other professional scan tool capable of reading manufacturer-specific symptom bytes.)
• C0045 0F: Left Rear Wheel Speed Sensor Circuit Signal Erratic. This suggests the signal is jumping or inconsistent, often caused by a damaged reluctor ring, debris on the sensor, or electrical interference. (see via GM Tech2, GDS2, or other professional scan tool.)
• C0045 18: Left Rear Wheel Speed Sensor Circuit Low Signal Amplitude. This indicates the signal from the sensor is too weak, which could be due to an excessive air gap between the sensor and ring, or an internal sensor fault. (see via GM Tech2, GDS2, or other professional scan tool.)
• C0045 5A: Left Rear Wheel Speed Sensor Circuit Not Plausible. The EBCM is receiving a signal, but it doesn't make sense compared to the other wheel speeds (e.g., three wheels at 30 mph, one at 0 mph). This often points to a damaged tone ring or significant wheel bearing play. (see via GM Tech2, GDS2, or other professional scan tool.)

Wiring & Ground Locations

• G110 — On the frame beneath the driver's side door. It is a critical ground for the EBCM.. A poor connection at this ground point can cause a loss of communication with the EBCM or trigger various ABS codes, including C0045. A GM TSB (#04-05-25-002D) specifically addresses cleaning this ground to resolve ABS issues.
• G300 — Below the driver's door, on the body mount.. This is another primary chassis ground for the Electronic Brake Control Module (EBCM). Corrosion or a loose connection here can lead to erratic EBCM behavior and false trouble codes.
• EBCM Connector — Located on the driver's side frame rail, below the driver's door.. The two wires from the left rear wheel speed sensor terminate here. For a C0045, the signal wire and low reference wire can be tested for continuity and shorts to ground/power at this connector, isolating the fault to the wiring or the EBCM itself.
• X411 Connector — Main chassis connector located on the left frame rail, often near the fuel tank area.. This is an intermediate connector between the rear sensor harness and the main body harness. It's exposed to the elements and is a known location for corrosion to develop, which can interrupt the signal from the left rear sensor.

Real Owner Repair Stories

• GM-Trucks.com forum user (2007-2014 Silverado/Sierra (platform level story)) — ABS and Stabilitrak lights on, code C0045.
  ❌ Tried (didn't work) Replacing the wheel speed sensor, Replacing the wiring pigtail
  ✅ What actually fixed it The root cause was excessive end play in the axle shaft. The movement of the axle allowed the reluctor ring to move too far from the sensor, causing the signal to drop out. The fix was to install a thicker C-clip inside the differential to reduce the axle's side-to-side movement.

OEM Part Supersession History

• 15121067 → 20763147, then 20938122 — Standard part updates for improved reliability or manufacturing changes.
  Heads up: The latest part number, 20938122, is the correct service replacement for all 2007-2014 GMT900 trucks and is interchangeable for both left and right rear positions.

Model Year Variations Within This Range

• 2014: The 2014 model year was a transition period. The older GMT900 platform was sold alongside the new K2XX platform. While both can have this code, the part numbers and diagnostic procedures may differ slightly. The information in this article primarily applies to the more common GMT900 trucks. The rear sensor on the K2XX is also a separate component.

Diagnostic Flowchart

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: For this repair, a used part is generally not recommended. The primary failure items are the electronic sensor and its wiring harness, which are wear items. A used sensor from a junkyard carries a high risk of being near the end of its life or already faulty.

Donor-vehicle mileage cap: roughly under 50000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• Verify the donor vehicle was not in a rear-end collision.
• Inspect the wiring for any signs of brittleness, cracking, or previous repairs.
• If possible, test the resistance of the used sensor with a multimeter before purchase; it should be within the 850-1350 Ohm range.

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

• Wheel Speed Sensor

Aftermarket brands forum-validated for this vehicle:

• ACDelco (GM Original Equipment)
• Delphi

Brands owners have reported issues with on this vehicle:

• Dorman (for sensors): Many forum and user reviews report Dorman sensors for this application being dead-on-arrival or failing prematurely. While Dorman wiring pigtails are often used successfully, their electronic sensors are considered a gamble by many technicians for this platform.

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 — Right Rear Wheel Speed Sensor Circuit. This is the companion code for the opposite side of the axle. A common diagnostic step is to swap the left and right sensors to see if the C0045 code changes to C0050, confirming a bad sensor.
• C0035 — Left Front Wheel Speed Sensor Circuit. A fault with any of the four wheel speed sensors will trigger similar symptoms, such as the ABS and Stabilitrak warning lights.
• C0040 — Right Front Wheel Speed Sensor Circuit. A fault with any of the four wheel speed sensors will trigger similar symptoms, such as the ABS and Stabilitrak warning lights.
• C0045-5A — Left Rear Wheel Speed Sensor Circuit - Plausibility Failure. This specific sub-code, noted in the diagnostic context, indicates the sensor's signal is present but doesn't match the speed data from other sensors, often due to debris on the sensor tip.
• C0045-0F — Left Rear Wheel Speed Sensor Circuit - Erratic Signal. This sub-code points to an inconsistent signal, which is a classic symptom of a failing sensor or a chafed wire making intermittent contact.
• U0121 — Lost Communication With Anti-Lock Brake System (ABS) Control Module. In cases of severe wiring damage to the WSS harness, such as a short to ground, it could potentially disrupt communication with the entire EBCM, triggering this code.

Frequently Asked Questions