About your Mercedes-Benz' safety features
Your Mercedes-Benz has a range of safety systems relying on sensors and safety mechanisms to ensure that your vehicle is working at its optimum performance while ensuring full protection for other road users and passengers.
We have created this simple guide to help you understand each of the common warning lights that may appear on your Mercedes-Benz. It is important that you know how to respond to each warning light to reduce any additional damage to your vehicle and to ensure that your vehicle is safe.
What the Mercedes-Benz warning light symbols mean
Red Lights
Brake System
Check if the handbrake is applied. If so, release the handbrake. If the light disappears, you can continue to drive as normal. If the light stays on, check your brake fluid level and fill up accordingly.*
Engine Cooling System
Wait until the engine has cooled down, make sure the air supply to the radiator has not been impaired. Avoid high loads on the engine and drive to the nearest authorised repairer, ensuring the coolant temperature remains below the red marking.
Engine Oil Pressure
Check the oil level. If the oil level is okay, contact Roadside Assistance. If the oil level is low, fill up accordingly*. Start the engine, and let it run for five seconds, then switch off the engine. If the light is still on contact Roadside Assistance.
Power Steering System
This indicated an issue with the power steering system. If safe to do so, continue driving to your nearest Mercedes-Benz authorised repairer. If the steering feels unsafe, please pull over when safe to do so and contact Roadside Assistance.
Airbag and Seatbelt System
There is a fault in the airbag or seatbelt system. If the warning lamp does not light up when the ignition is turned on, or if it lights up continuously/repeatedly during a journey, consult an authorised repairer immediately.
Vehicle Charging System
There is an alternator or electrical system fault in the vehicle. Switch off all consumer electrical products that may drain the battery further. If you cannot start the engine, contact Roadside Assistance.
Seatbelt Buckles
Check that the driver and front passenger has their seatbelt fastened properly. If the light disappears, this is a normal function. If the light does not disappear, contact an authorised repairer.
Refill Adblue
Stop the car as soon as it is safe to do so. The red warning light appears when there is no AdBlue range left. Once this happens, the car will not restart once the ignition is turned off. The system will need a full top-up before the car can be restarted.*
Bonnet
Check that the bonnet is closed properly. If the light disappears, this is a normal function.If the light does not disappear, contact an authorised repairer.
Boot Lid
Check the boot lid is closed properly. If the light disappears, this is a normal function. If the light does not disappear, contact an authorised repairer.
Mercedes SOS
At least one of the main functions of the Mercedes Me connect system or SOS emergency call system have malfunctioned. Please consult your nearest Mercedes-Benz dealership.
Yellow Lights
Emissions Control Light
This indicated an issue with the engine, exhaust system or fuel system. Remove the key for 30 seconds, then reinsert and start the engine. If the light disappears, the problem is rectified. Visit an authorised repairer for a check. If the light does return and the power is down, contact Roadside Assistance. If the light returns and the power is not down, take extra care and drive to an authorised repairer.
Attention Assist
This will illuminate when fatigue or a lack of concentration has been detected from the driver. If necessary, take a break. If the system continues to illuminate, consult a qualified workshop/repairer.
Parking Sensor Malfunction
The park assist PARKTRONIC system has been deactivated due either signal interference, dirty sensors or a malfunction. Turn the vehicle on and off, as well as ensure the sensors are clean. If the problem persists, contact a qualified repairer.
Glow Plug (Diesel)
If the light appears when the ignition is switched on, this is a normal function (to appear for a few seconds). If the light appears whilst the engine is running, drive slowly and carefully to an authorised repairer immediately due to engine management fault.
Engine Oil Level
This may indicate the oil level has either dropped or exceeded the recommend levels.If the oil level is below the recommend level, top-up the oil level above the minimum level.If oil level is above the maximum level, consult a qualified workshop as excess engine oil can damage the engine.
Anti-lock Braking System (ABS)
This is your Anti-Lock Braking System light. If this light illuminates, it will indicate the safety systems are currently not available, which result in longer emergency braking distances.Drive carefully to an authorised repairer.
Electronic Stability Programme (ESC)
If displayed permanently, switch off the ignition and then restart. If the light is still on, drive carefully to an authorised repairer. If it is flashing, this is a normal operating feature. No action is required.
Tyre Pressure Monitoring
This typically indicates low tyre pressures or a missing/faulty wheel sensor. If the tyre pressures are okay, and the light is still on, drive carefully to an authorised repairer to have the system examined.
Power Steering System
This indicated an issue with the power steering system. If safe to do so, continue driving to your nearest Mercedes-Benz authorised repairer. If the steering feels unsafe, please pull over when safe to do so and contact Roadside Assistance.
Brake Pad Monitoring
This is your brake pad warning light. Your brake pads are wearing thin, which may impact braking performance. Contact an authorised repairer to check the condition of your brake pads.
Airbag and Seatbelt System
There is a fault in the airbag or seatbelt system. If the warning lamp does not light up when the ignition is turned on, or if it lights up continuously/repeatedly during a journey, consult an authorised repairer immediately.
Automatic Gearbox
This is your gearbox malfunction light. A message may appear – follow the instructions and drive to an authorised repairer immediately as long as it is safe to do so. If this is not possible, contact Roadside Assistance. If the message asks you to stop the vehicle and select P, contact Roadside Assistance.
Smart Key
The warning light will indicate a number of issues with the smart key including the battery discharging, key not being detected and can also be to warn you to take your key when leaving the vehicle (a warning may also sound). Consult a qualified authorised repair.
Suspension Dampers
Malfunction has been detected with the suspension system which may impact vehicle handing characteristics. Drive appropriately below 50mph to the nearest qualified workshop. Contact an authorised repairer.
Active Brake Assist
Active brake assist consists of the following functions, distance warning function, autonomous braking function, situation dependent braking assist and evasive steering assist. If this warning light appears, all or some of the safety systems may not be functioning. If all sensors are clear and free of dirt, please consult a qualified repairer.
Downhill Speed Regulation
This includes the downhill speed system regulation is in use or is malfunctioning. If the system is in use, the maximum speed is 25mph and the light will flash if the speed is exceeded. Contact an authorised repairer.
Headlight Range Control
There is a headlight range control system fault. Contact an authorised repairer.
Low / High Beam
This indicated whether the headlights are on low or high beam. If the headlights are set to automatic, the light will automatically appear when dark. Contact an authorised repairer.
Low Fuel Level
The fuel level has dropped into the reserve. Please refuel as soon as possible. If you do have fuel, this could indicate the fuel cap is loose.
Active Lane Assist
This light will appear when lane assist is switched on and road markings cannot be detected. If this light is accompanied by a 'system fault' message, contact an authorised repairer.
Hold Handbrake System
The hold function has been activated. This is normally activated by pressing hard on the brake while the transmission is in drive mode. To disengage hold, press the accelerator pedal. If this continues to illuminate, please seek an authorised repairer.
Windscreen Washer Fluid
The windscreen washer fluid reservoir needs filling. Top up the fluid for the windscreen washer. Refer to the owner’s manual.
Rear Fog Lights
This warning light will appear when the rear fog lights are switched on. Only operate the rear fog lights in foggy conditions to avoid dazzling other drivers.
Cruise Control
The cruise control light will appear when the cruise control system is activated. This is a normal operating feature of the system. Refer to the owner’s manual or contact your nearest authorised repairer for an explanation of the operation of the system.
Headlight Warning
You are leaving your vehicle with the headlights still on. Turn the light switch position to off or auto. If this does not result in the light turning off, the lighting system may be a fault. Please contact an authorised repairer.
*Refer to owner’s manual or seek professional assistance.
The information on warning lights on this page does not apply to electric cars. Please consult your owner's manual.