2011 Buick Enclave Owner's Manual - Page 273

Driving and Operating When the System Does Not Seem to Work Properly If the URPA system does not activate due to a temporary condition, the message PARK ASSIST OFF or PARK ASST BLOCKED SEE OWNERS MANUAL will be displayed on the DIC. SERVICE PARK ASSIST: If this message occurs, take the vehicle to your dealer to repair the system. PARK ASSIST OFF: This message occurs if the driver disables the system. PARK ASST BLOCKED SEE OWNERS MANUAL: This message can occur under the following conditions: . . 9-35 The ultrasonic sensors are not clean. Keep the vehicle's rear bumper free of mud, dirt, snow, ice and slush. For cleaning instructions, see Exterior Care on page 10‑88. The park assist sensors are covered by frost or ice. Frost or ice can form around and behind the sensors and may not always be seen; this can occur after washing the vehicle in cold weather. The message may not clear until the frost or ice has melted. A trailer was attached to the vehicle, or a bicycle or an object was hanging out of the liftgate during the last drive cycle. Once the attached object is removed, URPA will return to normal operation. A tow bar is attached to the vehicle. The vehicle's bumper is damaged. Take the vehicle to your dealer to repair the system. Other conditions may affect system performance, such as vibrations from a jackhammer or the compression of air brakes on a very large truck. . . . .