Code C0660 on the 2020 GMC Acadia indicates a malfunction in the front left ride height sensor. This sensor is part of the automatic leveling or adaptive suspension system, measuring vehicle ride height to enable load-leveling or adjust damping characteristics.
Ride Height Sensor Function
Ride height sensors measure the distance between the vehicle body and the suspension arm at each corner. This data tells the suspension control module how the vehicle is loaded and positioned. Systems use this information for automatic load leveling, headlight auto-leveling, or adaptive damper adjustment. The front left sensor monitors one corner of this critical measurement network.
Observable Symptoms
With C0660 active, the suspension or ride control warning light illuminates. If equipped with adaptive suspension, the system may default to a fixed setting. Automatic load leveling may not function, leaving the vehicle sitting lower or higher than normal when loaded. Headlight auto-leveling may also be affected.
Diagnostic Process
The ride height sensor mounts near the front left control arm or suspension link, using a lever arm to translate vertical movement into rotational sensor input. Check the sensor linkage for disconnection or damage - a common failure point. The sensor itself can fail internally, and the wiring route along the suspension is susceptible to damage from road debris.
Repair Considerations
If the linkage has disconnected, it may simply need reconnection. Broken linkages require replacement. Failed sensors require removal from the suspension area - this may involve removing the wheel and accessing the lower control arm area. After sensor replacement, some systems require calibration to establish reference heights.