2004 Mercedes CL-Class Owner's Manual - Page 219

Controls in detail Driving systems Parktronic malfunction There is a malfunction in the Parktronic system if the red segments of the Parktronic warning indicator come on and a warning sounds. The Parktronic system will switch itself off after 30 seconds and the indicator lamp on the Parktronic switch comes on. Have the Parktronic system checked by an authorized Mercedes-Benz Center as soon as possible. or Check Parktronic operation at another location to rule out interference from outside radio or ultrasonic signals. If only the red segments of the Parktronic warning indicator come on and no warning sounds, then the sensors of the Parktronic system are dirty or malfunctioning. Malfunction may also be caused by interference from other radio or ultrasonic signals. The Parktronic system will switch itself off after 20 seconds. Clean Parktronic system sensors ( page 287). Switch on ignition. 218