What causes the automatic start-stop system failure in the Sagitar engine?

[DelKate]

The reasons for the automatic start-stop system failure in the Sagitar engine are: insufficient battery power of the vehicle, which prevents the automatic start-stop function from meeting the activation conditions; damage to the automatic start-stop switch; issues with the automatic start-stop sensor. These problems require maintenance and repair, otherwise they will affect the normal use of the vehicle's battery, leading to power loss and situations where the vehicle cannot start. Taking the 2021 Sagitar as an example, it is a compact car with body dimensions of: length 4753mm, width 1800mm, height 1462mm, a wheelbase of 2731mm, a fuel tank capacity of 50 liters, and a curb weight of 1355kg.

[DelEden]

A few days ago, my friend's Sagitar also encountered this issue. After pondering for a while, we realized the key lies in the battery. The auto start-stop system is particularly sensitive to voltage—if the battery is aging or the charge is below 80%, it's likely to stop working. You can first check if there's any warning on the dashboard during startup, like a yellow flashing 'A' with an arrow. Daily habits also affect its operation; for instance, if you turn on the heater before the engine reaches optimal temperature, or if the steering wheel angle exceeds 30 degrees during a turn, the system will automatically disable the start-stop function. If the battery has been in use for three to four years, it's wise to test its health. If the remaining capacity drops below 70%, replace it immediately—don't wait until you're stranded on the road like my neighbor, who regretted not acting sooner.

[SanEva]

As a seasoned driver who has owned three generations of Sagitar, I can say that most automatic start-stop failures stem from sensor issues. The brake vacuum sensor near the coolant reservoir at the front is particularly prone to dust buildup—simply unplugging and cleaning its metal contacts might revive it. Dirty wheel speed sensors under the car can also trigger false alarms, especially after rainy seasons. Once, a dealership spent three days diagnosing my car only to find that an aftermarket dashcam was draining power and causing voltage fluctuations; removing it fixed the issue instantly. Remember, avoid randomly installing additional electronics—VW’s system is highly sensitive.

[IslaFitz]

According to the maintenance manual, the start-stop system has 12 triggering conditions, and the most easily overlooked one is the air conditioning setting. When the difference between the actual temperature inside the car and the set temperature exceeds 3°C, or if the front defogging function is activated, the engine will be forced to run. Pressing the brake too lightly or shifting to S mode will also disable the system. Try pressing the brake pedal all the way down when waiting at a red light; if the green "A" light comes on, it means the system is on standby. If it still doesn't work, you'll need to use a diagnostic tool to check for trouble codes. The B126D battery sensor fault is quite common in the Sagitar.