Start/stop function

With the start/stop function, the engine switches off temporarily when the car has stopped e.g. at traffic lights or in a traffic queue, and then starts again when it is needed.

The start/stop function reduces fuel consumption, which in turn can contribute to an environmentally conscious driving style and reduced emissions.

Points to remember when using the start/stop function

For the start/stop function to work requires that a number of conditions are met.

The start/stop function is not activated

One or more criteria may mean that the engine is not switched off/the function is not activated.

  • the driver has not fastened the seatbelt
  • the car has not been able to reach a speed of approx. 10 km/h (6 mph) after starting, or the function has been activated a number of times successively
  • the engine has not reached normal operating temperature
  • the outside temperature is below approx. -5 °C (23 °F) or above approx. 30 °C (86 °F)
  • the windscreen's electric heating is activated
  • the environment in the passenger compartment deviates from the set values
  • the driver is making large steering wheel movements
  • the road is very steep
  • the bonnet is opened
  • the ABS system has been activated
  • in the event of heavy braking (even without the ABS system having been activated)
  • the capacity of the starter battery has fallen below the minimum permissible level
  • many starts during a short period of time have activated the starter motor's thermal protection
  • the exhaust system's particulate filter is full
  • a trailer is connected to the car's electrical system.

 Note

High current take-off may lead to battery capacity falling below the lowest permitted level, which temporarily limits the start/stop function. The engine then starts automatically without the driver lifting his/her foot from the brake pedal.

The start/stop function is not deactivated

One or more criteria may mean that the engine is not started/the function is not deactivated.

For cars with automatic gearbox:
  • the driver has not fastened the seatbelt
  • gear position P is engaged and the driver door is open.

The start/stop function is deactivated without the brake pedal being released

In the following cases, the function may be deactivated and the engine started without the driver releasing the brake pedal:

  • high humidity in the passenger compartment forms misting on the windows
  • the environment in the passenger compartment deviates from the set values
  • repeated pumping of the brake pedal
  • the bonnet is opened
  • the capacity of the starter battery has fallen below the minimum permissible level
For cars with automatic gearbox:
  • the driver's seatbelt is unbuckled and the gear selector is in position D or N
  • the gear selector is moved from position D to position R or M
  • the driver door is opened with the gear selector in position D.

 Warning

Do not open the bonnet when the start/stop function is active. Switch off the engine normally before raising the bonnet.