Driver assistance systemsProblem Possible causes/consequences and M Solutions· Red warning lampis lit.Warning tone sounds.Forward collision warning detects an obstacle on the road.X Pay careful attention to the road and traffic conditions and beready to brake.^ Yellow warninglamp lights up whiledriving.Distance WarningInoperative or Elec‐tronics MalfunctionVisit Workshopappears.The sensors in the radiator trim are dirty.X Clean the sensors.Environmental influences or error sources outside the system aretemporarily interfering with the forward collision warning. Pos-sible causes are:Rheavy rain or snowRoperating temperature is too highRon-board voltage is too lowForward collision warning is operational again when the causeslisted no longer apply.Warning lamp remains lit.X Pull over and stop the vehicle, paying attention to road andtraffic conditions.X Clean the sensors.X Restart the engine.Warning lamp still remains lit.X Consult a qualified specialist workshop.^ and C as wellas other warning lampsare lit.Central vehicle electronics system is malfunctioning.After switching off the engine, it is no longer possible to lock orunlock the doors using the remote control on the SmartKey or tostart the engine.X Pull over and stop the vehicle, paying attention to road andtraffic conditions.X Consult a qualified specialist workshop.180 Driver assistance systems>> Practical advice.