What is code c0040

Hi, this is Bo, an auto expert on RepairPal's Car Genius team! Code C0040 on your 2005 GMC Yukon XL 1500 points to an issue with the *Right Front Wheel Speed Sensor Circuit*. This sensor is part of your ABS system and helps monitor wheel rotation to prevent skidding during braking. When this code pops up, it usually means the ABS module isn’t getting a proper signal from that sensor. Possible culprits include: 1. A damaged or dirty wheel speed sensor—road grime or a rock can wreak havoc. 2. Frayed or corroded wiring to the sensor. 3. An issue with the tone ring on the wheel hub—if it’s cracked or covered in debris, the sensor can’t read it correctly. Start by inspecting the right front wheel area for obvious damage or dirt. If all looks good, a mechanic with an advanced scan tool can pinpoint whether it’s the sensor, wiring, or the ABS module itself. If you need any further advice or want help finding a trusted RepairPal shop in your area, please feel free to call us at 877-913-1554.