Start-Stop system: the essential guide

The Start-Stop system has been gaining a prominent role in our efficient driving habits as car manufacturers have implemented it in more and more models.

However, many drivers wonder if it really is an effective system or if, on the contrary, it poses a disadvantage for the mechanics or operation of the car.

Do not worry

Throughout this article, we are going to explain everything you need to know about this innovative system designed to promote fuel economy , including how to use it efficiently.

What is the Start Stop system?

The Start-Stop –also known as Start & Stop- is a system that stops the combustion engine when it detects the right conditions, such as stopping at a traffic light.

The engine stops completely in the mode known as stand by, waiting for the driver to express his willingness to continue driving.

It consists of an electronic detection system, as well as a reinforced battery and starter motor.

The latter is due to the fact that the number of starts that the engine is going to make during a journey is predictably higher than in a vehicle without this system.

How does the Start-Stop system work?

Start-Stop systems work in such a way that the engine stops automatically when any of the following occurs:

  • When the vehicle has exceeded 5km / h and is not driving in reverse.
  • When the vehicle has stopped or its speed is below 3 km / h.
  • Also, the gearbox must be in neutral and the clutch pedal is not depressed. The latter applies only to vehicles with a manual gearbox.


On the other hand, the system continually evaluates compliance with a series of safety conditions essential for its operation. They are as follows:

  • The hood must be fully closed, so visibility is optimal.
  • The driver’s door must be closed, as well as your seat belt properly fastened.
  • The battery must have a sufficient charge. Otherwise, the engine will continue to run for the alternator to charge the battery.
  • The motor must have reached the minimum required temperature (between 20 ° C and 50 ° C). Otherwise, poor lubrication will reduce its service life.
  • The temperature of the coolant and the exhaust system must be kept below critical levels.
  • The ambient temperature is neither low nor high (between 3 ° C and 55 ° C), which could reduce or raise the temperature of the stopped engine very quickly.
  • The air conditioning, climate control or windshield defroster systems are not working at their maximum, both because they require electrical power, and because their shutdown may affect safety or comfort. In the latter case, it is possible to change the Start-Stop setting to stop the engine, deactivating the air conditioning.
  • The vacuum level of the brake booster system and power steering is adequate (above 500 hPa). This is because the engine running and on hold assists the brake booster operation. After heavy braking, it may be necessary for the engine to keep running.
  • The self-cleaning system of the diesel engine particulate filter has not activated.


As you can see, these requirements are intended to prevent the Start-Stop system from functioning:

  • Put your safety at risk while driving.
  • Damage car mechanics.
  • Make it difficult to restart walking or parking maneuvers
  • Generate higher fuel consumption.

How to use the Start Stop system efficiently?

Regardless of whether all the conditions mentioned above are met, it may be the case that driving conditions advise against the use of Start-Stop.

You must bear in mind that, despite having a reinforced mechanics, the continuous stops and starts shorten the useful life of the engine.

To avoid this, there are a series of circumstances in which we advise you to deactivate the system or inhibit its operation (pressing the clutch and / or putting the neutral gear):

Approach to a red traffic light

What is to be done:

Approaching a red light should take place by taking advantage of the car’s inertia and allowing it to decelerate as a result of the engine brake. In this way, zero fuel consumption is achieved.

Once the stop zone is reached, the brake is applied and the Start-Stop system is allowed to stop the engine, before restarting.

What should not be done:

It does not make sense to accelerate the march in order to reach the vehicle stop line earlier so that the Start-Stop system stops the engine sooner.

The fuel savings you will achieve will be less than the extra consumption generated by the acceleration of the engine.

Stop at a red light

What should not be done:

There is a bad habit among some drivers, consisting of keeping the clutch depressed and the first gear engaged while stopping at a traffic light.

This not only damages the clutch mechanics, but also prevents the Start-Stop system from stopping the engine.

What is to be done:

As soon as you reach the stop line at the stoplight, you should put the gearbox in neutral and release the clutch.

Intersections and junctions with fluid traffic

While going through intersections and crossings, it is very possible that the vehicle stop will be very brief.

What is to be done:

Step on the clutch pedal to prevent the Start-Stop system from stopping the engine.

Retentions and traffic jams with continuous stops

Traffic during retentions, caravans and traffic jams is characterized by a succession of continuous stops and starts that hardly last a few seconds.

What is to be done:

Unless you foresee that the vehicle will be immobilized for a long time, it is best to deactivate the Start-Stop system.

How to deactivate the Start-Stop?

Disabling the Start-Stop system is very simple.

You just have to press the button located on the dashboard.

As a general rule, the control panel will indicate whether the system is operational or not. For this, the term “ECO” is often used. However, keep in mind that, even if the system is activated, it will not start working until the circumstances mentioned at the beginning of this article occurred.

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