C0045 on GMC
Left Rear Wheel Speed Sensor Circuit
C0045 on GMC vehicles indicates left rear wheel speed sensor circuit. Au7o has documented this code across 3 GMC models — most commonly on Acadia, Sierra 1500, Terrain. This is a brake/ABS-system code. Each wheel has a speed sensor that tells the anti-lock brake (ABS), traction control, and stability systems how fast that wheel is turning. C0045 means the ABS module has detected an electrical problem in the circuit for the left rear wheel speed sensor — such as an open, short, or signal that's missing or out of range. As a result you'll typically see the ABS and traction/stability warning lights, and those safety features may be temporarily disabled even though your normal brakes still work. Typical repair costs on GMC range from $150 to $1,500, depending on the specific model and root cause.
Common Causes of C0045
- •Failed left rear wheel speed sensor
- •Damaged, corroded or disconnected sensor wiring/connector
- •Damaged or contaminated tone/reluctor ring (rust, debris, missing teeth)
- •Excessive air gap between sensor and tone ring
- •Wheel bearing wear affecting the sensor (on bearing-integrated sensors)
- •Water intrusion or corrosion in the connector
- •Faulty ABS control module (less common)
C0045 on GMC by Model
GMC Acadia(1 issue)
- Front and Rear Wheel Hub Bearing Assembly Failure With Integrated ABS Tone Ring Degradation2007-2018
The Lambda-platform hub bearing assemblies wear early — owners report failures well under 60,000 miles and, on the rear, repeat failures on the same vehicle. Two distinct symptoms come from one part: mechanical noise (a speed-dependent hum or growl that changes when the vehicle is loaded in a turn) and an ABS fault, because the encoder/tone ring on GM Lambda hubs is magnetically printed onto the bearing's inner race surface. When that magnetic layer degrades or sloughs off, the ABS module gets an implausible wheel speed signal and posts a wheel speed sensor code even though the sensor itself is fine — which is why replacing the sensor does not fix it.
GMC Sierra 1500(1 issue)
- Electronic Brake Control Module Failure2014-2023
The electronic brake control module (EBCM) experiences failures causing ABS, traction control, and stability control systems to malfunction. Issues range from warning lights illuminating to complete system failures. The 2023 models have a specific recall for software that may fail to display a warning light when brake fluid loss occurs.
GMC Terrain(1 issue)
- Wheel Bearing / Hub Assembly Magnetic Encoder Ring Failure - ABS and Traction Lights Without Bearing Noise2010-2024
Terrain front and rear hub assemblies integrate the ABS magnetic encoder ring into the bearing's inboard seal, where it sits directly exposed to road salt and moisture. Two distinct failure modes result. The mechanical one is the familiar humming or roaring that rises with speed and changes when loading the bearing in a wide turn. The one that fools owners and shops is encoder-ring failure on a bearing that is still mechanically tight and silent: the wheel speed signal drops out and the vehicle sets a wheel speed sensor code with ABS, traction control and stability control disabled. Replacing only the external sensor does not fix it, because the encoder is part of the bearing. Both generations are affected, with salt-belt vehicles failing earliest.
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View C0045 across all makes →Frequently Asked Questions
What does C0045 mean on GMC?▼
C0045 stands for "Left Rear Wheel Speed Sensor Circuit." This is a brake/ABS-system code. Each wheel has a speed sensor that tells the anti-lock brake (ABS), traction control, and stability systems how fast that wheel is turning. C0045 means the ABS module has detected an electrical problem in the circuit for the left rear wheel speed sensor — such as an open, short, or signal that's missing or out of range. As a result you'll typically see the ABS and traction/stability warning lights, and those safety features may be temporarily disabled even though your normal brakes still work. On GMC specifically, this code is documented across 3 models.
What causes C0045 on GMC vehicles?▼
Common causes on GMC: Failed left rear wheel speed sensor, Damaged, corroded or disconnected sensor wiring/connector, Damaged or contaminated tone/reluctor ring (rust, debris, missing teeth), Excessive air gap between sensor and tone ring, Wheel bearing wear affecting the sensor (on bearing-integrated sensors). Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix C0045 on a GMC?▼
Repair costs on GMC range from $150 to $1,500, depending on the specific model and root cause.
Which GMC models have C0045 documented?▼
Au7o has documented C0045 on 3 GMC models: Acadia, Sierra 1500, Terrain.