29Keys, doors, windows, sunroofFaultIf the central locking system cannot beopera ted with the remote control, it m ay b edue to the following :z The range of the rem ote control hasbeen ex ceeded.z Remote control b attery v olta ge is toolow. Battery replac ement - see nextcolumn.z Freq uent, rep eated opera tion of theremote control outside the receptionra nge of the vehicle (e.g. too far fromvehicle, rem ote control is then no longerrecognised). Remote controlsynchronisation – see end column.z If the centra l loc king sy stem isov erloaded as a result of repeatedop eration at short interv als. The powersupply is c ut off for a b rief period.z Interference from higher-power radiowaves from other sources.To elim inate the cause of a fault, werecom mend contacting a workshop forassistance.Manual unlocking and locking using thevehic le key - see page 33.Rem ote control b attery rep lacementReplace the battery as soon as the rangeof the rem ote control becom es reduced.Extending the key – see page 26.Open the remote c ontrol. Replace thebattery (b attery ty pe – see page 307),noting insta lla tion position. Close theremote control.Mak e sure that you dispose of old batteriesin accordance with env ironmentalprotec tion regulations.Remot e cont rol synchronisati onAfter a battery change, unlock door withkey in lock - see page 33. Inserting the keyinto the lock sy nc hronises the remotecontrol.