Modern cars are equipped with a variety of electronic assistants designed to save fuel and reduce harmful emissions into the atmosphere. One such solution is an automatic engine start and stop system known as Start-Stop. Many drivers notice a symbol on the dashboard or center console that represents the letter And in a circle. This indicator signals the operating status of the system and often raises questions among car owners who are accustomed to a classic set of light bulbs.
The appearance of this icon does not always indicate a malfunction. In normal mode, it informs that the system is active and ready for operation, or that the engine was automatically turned off at a traffic light. However, if the symbol is flashing, amber, or crossed out, the battery may need to be charged or the sensors may be malfunctioning. Understanding the logic of the operation of this unit will allow you to avoid unnecessary panic and correctly respond to signals from the on-board computer.
In this article we will look in detail at how exactly the mechanism functions. Start-Stop, why it can turn off on its own and whether it’s worth trying to deactivate it programmatically. We will also consider the impact of this system on the life of the starter and battery, since these aspects are often the most worrying for car owners.
The main purpose of the Start-Stop system
The main task of the system denoted by the symbol And in the circle, is to save fuel during city traffic jams and long stops at traffic lights. When the car stops, the electronics shut down the engine, preventing it from idling. As soon as the driver releases the brake pedal or squeezes the clutch, the engine instantly starts again. This allows you to reduce fuel consumption in the urban cycle by up to 10-15% and reduce noise levels.
It is important to understand that starting the engine in such conditions is carried out by a reinforced starter, designed for tens of thousands of switching cycles. A regular starter would simply burn out after a month of such use. In addition, vehicles with this system often use a battery type AGM or EFB, which are able to withstand deep discharges and quickly restore charge.
The system is integrated into the overall engine control network and constantly analyzes many parameters. If at least one of them is outside the permissible limits, an automatic stop will not occur, and the driver will see a corresponding notification on the display. This is done so as not to create discomfort and not disrupt the operation of other vehicle systems.
Interpretation of indicator states
Indicator with letter A can be displayed in different colors and flashing modes, which carries specific information to the driver. Green color usually means that the system is active and the engine is currently turned off. If the yellow indicator is on, this most often indicates that the system is ready for operation, but the engine has not yet been stopped, or the conditions for stopping have not yet been met.
Particular attention should be paid to cases where the icon is crossed out or surrounded by additional symbols. This is a direct signal that the system is forcibly deactivated. The reasons can be different: from low battery charge to low antifreeze temperature. Some models BMW or Audi A flashing indicator may indicate a malfunction of the control module itself.
⚠️ Attention: If the indicator Start-Stop lights up yellow with the inscription “Fault” or “Malfunction” and does not go out after starting the engine, it is necessary to carry out computer diagnostics. Ignoring this error may result in a deep battery discharge.
Below is a table to help you quickly navigate the indicator values on the dashboard of various manufacturers:
| Indicator type | Color | Meaning |
|---|---|---|
| And in a circle with an arrow | Green | The engine is stopped by the system, ready to start |
| And in the circle | Yellow/Orange | The system is active, but the conditions for stopping are not met |
| And in a circle with a cross | Yellow | The system is disabled manually or automatically due to conditions |
| And in the circle it blinks | Yellow/Red | System malfunction or critical battery charge |
Why the system does not work: main reasons
Often drivers are faced with a situation where the system Start-Stop stops turning off the engine at traffic lights. This is not always a failure. The electronic control unit (ECU) receives data from dozens of sensors and prohibits stopping the engine if this could harm the car or the comfort of passengers. For example, if the interior temperature is too low and the heater is running at full power, the engine will run to warm up the antifreeze.
One of the most common causes of failure is the condition of the battery. The Battery Monitoring System (BMS) monitors the state of charge. If the charge drops below a certain threshold (usually around 70-75%), the ECU inhibits automatic stops to ensure that the next restart can be reliably started. Temperature also has an impact: in severe frost or, conversely, when the engine overheats, the system is blocked.
- 🔋 Low battery charge: The battery has not gained sufficient capacity after the previous start or long period of inactivity.
- 🌡️ Temperature: The engine is cold or, conversely, is operating under high load (air conditioning, heated windows).
- 🚗 Steering wheel position: When the steering wheel is turned all the way, the system may not be activated for safety reasons.
- 🏔️ Terrain: When driving uphill with a steep slope, the system may not turn off the engine to avoid rolling back.
The influence of fuel quality on Start-Stop
Fuel quality also plays a role. If the ECU detects unstable combustion or low octane, it can temporarily disable the economy system to prevent detonation upon restart and protect the catalysts from rapid failure.
How to disable the auto stop feature
Many drivers prefer to disable the system Start-Stop immediately after starting the engine, as they find its operation annoying in heavy traffic. The easiest and most legal way is to use a standard button. It is usually located on the center console next to the gearshift lever or on the climate control panel. It shows the same letter A in a circle with the inscription "OFF".
Pressing this button deactivates the system only for the current ignition cycle. This means that after you turn off the car and start it again, the system Start-Stop is activated by default and you will have to press the button again. This is a requirement of environmental standards, which oblige manufacturers to include savings by default.
There are also software ways to disable it through the multimedia menu or diagnostic adapters, but they can be difficult for the average user. Some models Volkswagen or Skoda You can change the priority of the air conditioning system, which will indirectly affect the frequency of operation of the system.
☑️ Manual shutdown algorithm
Influence of the system on the service life of car parts
Around the system Start-Stop There are many myths that it “kills” the engine and starter. In fact, engineers plan for increased service life for components operating in such conditions. The starters are equipped with more wear-resistant brushes and bendixes, and the crankshaft liners have a special coating that preserves the oil film during frequent starts.
The battery really takes the brunt of it. Conventional acid battery WET will quickly fail in conjunction with this system. Therefore, replacement is required exclusively for batteries with technologies AGM (Absorbent Glass Mat) or EFB. Installing a cheap analogue will lead to the fact that after six months the system will stop working, and the battery itself will require replacement.
⚠️ Attention: When replacing the battery on vehicles with Start-Stop Often a procedure for “binding” a new battery through a diagnostic scanner is required. Without this, the control unit may incorrectly estimate the charge, which will lead to constant errors or undercharging.
As for the engine, the main wear occurs precisely at the moment of startup, when the oil has not yet been completely distributed among the rubbing pairs. However, modern motor oils labeled 5W-30 or 0W-20 have excellent fluidity even during cold starts, minimizing this effect. Statistics from service centers do not show a critical increase in breakdowns of engines equipped with a start-stop system.
Diagnostics and troubleshooting
If the system stops working and the indicator lights up yellow with an error message, it is necessary to carry out diagnostics. The first step should always be to check the voltage at the battery terminals. If the voltage is below 12 Volts with the engine off, the system needs to be charged with an external device or driven over a long distance without using powerful energy consumers.
The second important step is to check the negative current sensor, which is often installed on the negative terminal of the battery. Oxidation of the contacts or damage to the wiring of this sensor leads to the fact that the ECU “does not see” the battery and blocks operation Start-Stop. It is also worth checking the integrity of the fuses responsible for the starter control circuit.
In cases where simple methods do not help, you need to connect a professional scanner OBD-II. It will allow you to read the exact error code from the engine management system. This could be a malfunction of the vacuum pump (for diesel engines), problems with the brake pedal position sensor, or failures in the software of the control unit.
Helpful tip: Before going to the service center, try to fully charge the battery with an external charger for 12-24 hours. In 60% of cases, this returns the system to functionality without the need to replace parts.
Main conclusion: The Start-Stop system is a complex complex that depends on the condition of the battery and temperature. Most often, its failure is temporary and does not require expensive repairs.
Is it possible to permanently disable the Start-Stop system?
Physical shutdown (breaking the button circuit) is possible, but can lead to errors in the on-board network. Software shutdown via flashing (chip tuning) is more reliable, but voids the car’s warranty and may affect the environmental class when passing inspection in some countries.
Why doesn't the system work in winter?
In winter, the system works less actively or does not work at all, as the electronics prioritize charging the battery, which loses capacity in the cold, and maintains engine temperature for efficient operation of the stove and catalyst.
The Start-Stop error came on after replacing the battery. What to do?
Most likely, the adaptation (training) procedure for the new battery was not carried out. You need to connect a diagnostic scanner and in the “Body” or “Engine” menu find the “Battery replacement” or “BMS adaptation reset” item.
Does frequent starting harm the 1.6 or 2.0 engine?
Modern engines with a volume of 1.6–2.0 liters are designed for a service life of 250-300 thousand km or more. Frequent starts within the Start-Stop system do not have a critical impact on the engine life if recommended oils and high-quality gasoline are used.