BMW 3 Owners & Service Manuals

BMW 3: Auto Start/Stop function

Concept

The Auto Start/Stop function helps save fuel.

The system switches off the engine during a stop, for instance in traffic congestion or at traffic lights. Drive-ready state remains switched on.

The engine starts automatically for driving off.

General information

After each engine start using the Start/Stop button, the Auto Start/Stop function is ready. The function is activated from speeds of approx.3 mph/5 km/h.

Depending on the selected driving mode, the system is automatically activated or deactivated.

Engine stop

Functional requirements

Steptronic transmission

The engine is switched off automatically during a stop under the following conditions:

  • The selector lever is in selector lever position D.
  • The brake pedal remains pressed while the vehicle is stationary or the vehicle is held by Automatic Hold.
  • The driver's safety belt is buckled or the driver's door is closed.

Steptronic transmission: manual engine stop

If the engine was not switched off automatically when the vehicle stopped, the engine can be switched off manually:

  • Press the brake pedal forcefully again from the current pedal position.
  • Engage selector lever position P.

If all functional preconditions are fulfilled, the engine switches off.

Air conditioner when the engine is switched off

The air flow from the air conditioner is reduced when the engine is switched off.

Displays in the instrument cluster

General information

The display in the tachometer indicates that the Auto Start/Stop function is ready for an Automatic engine start.

The display indicates that the conditions for an automatic engine stop have not been met.

Total time with switched-off engine

ECO PRO, driving mode: depending on the vehicle equipment, the total time that the engine has been switched off using the Auto Start/ Stop function is displayed on an automatic engine stop.

The total time can be reset via the trip data.

Functional limitations

The engine is not switched off automatically in the following situations:

  • In case of a steep downhill grade.
  • Brake not engaged strongly enough.
  • The external temperature is high and automatic climate control is running.
  • The car's interior has not yet been heated or cooled to the required level.
  • Where there is a risk of window condensation when the automatic climate control is switched on.
  • Engine or other parts not at operating temperature.
  • Engine cooling is required.
  • The wheels are at a sharp angle or the steering wheel is being turned.
  • Vehicle battery is heavily discharged.
  • At higher elevations.
  • The hood is unlocked.
  • The parking assistant is activated.
  • Stop-and-go traffic.
  • Steptronic transmission: selector lever position in N or R.
  • After driving in reverse.
  • Use of fuel with high ethanol content.

Starting the engine

Functional requirements

Steptronic transmission

The engine starts automatically under the following preconditions:

  • By releasing the brake pedal.
  • When Automatic Hold is activated: press the accelerator pedal.

Driving off

After the engine starts, accelerate as usual.

Safety mode

After the engine switches off automatically, it will not start again automatically if any one of the following conditions are met:

  • The driver's safety belt is unbuckled and the driver's door is open.
  • The hood was unlocked.

Some indicator lights light up for a varied length of time.

The engine can only be started via the Start/Stop button.

System limits

Even if driving off was not intended, the deactivated engine starts up automatically in the following situations:

  • Excessive warming of the car's interior when the air conditioning is switched on.
  • Excessive cooling of the car's interior when the heating is switched on.
  • Where there is a risk of window condensation when the automatic climate control is switched on.
  • The steering wheel is turned.
  • Steptronic transmission:
    Change from selector lever position D to N or R.
  • Steptronic transmission:
    Change from selector lever position P to N, D, or R.
  • Vehicle battery is heavily discharged.
  • Start of an oil level measurement.

Intelligent Auto Start/Stop function

Depending on the vehicle equipment and country- specific version, the vehicle features a variety of sensors for assessing the traffic situation. The Intelligent Auto Start/Stop function uses this information to adapt to various traffic situations in a proactive manner.

For instance, this applies to the following situations:

  • If a situation is detected in which the stopping time is expected to be very short, the engine is not switched off automatically. A message appears on the Control Display, depending on the situation.
  • If a situation is detected in which the vehicle needs to drive off immediately, the engine is started automatically.

The function may be restricted if the navigation data is invalid, outdated or not available, for example.

Activating/deactivating the system manually

Concept

The engine is not automatically switched off.

The engine is started during an automatic engine stop.

Using the button

Driving

Press the button.

Steptronic transmission: via selector lever position

The Auto Start/Stop function is also deactivated in selector lever position M/S.

Via the Driving Dynamics Control

The Auto Start/Stop function is also deactivated in SPORT driving mode of the Driving Dynamics Control.

Display

  • LED comes on: auto Start/Stop function is deactivated.
  • LED goes out: auto Start/Stop function is activated.

Switching off the vehicle during an automatic engine stop

General information

During an automatic engine stop, the vehicle can be switched off permanently, for instance when leaving it.

Steptronic transmission

1. Press the Start/Stop button.

  • Drive-ready state is switched off.
  • Standby state is switched on.
  • Selector lever position P is engaged automatically.

2. Set the parking brake.

Automatic deactivation

General information

In certain situations, the Auto Start/Stop function is deactivated automatically for safety reasons, for instance if no driver is detected.

Malfunction

The Auto Start/Stop function no longer switches off the engine automatically. A Check Control message is displayed. It is possible to continue driving. Have the system checked by a dealer's service center or another qualified service center or repair shop.

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