I've noticed that many of our workshop customers and my social media followers don't fully understand how the car start stop system works and have serious concerns about it. Questions such as "Will my car start again when I stop at traffic lights?", "What if the engine cuts out in the middle of a junction and won't restart?" and "Will all those extra starts wear out my starter motor faster?" are common. In most cases, these concerns are unfounded and stem from a misunderstanding of how the system actually works. That's why I've written this article: to answer some of the most common questions and help you feel more confident and at ease when using your Start/Stop system. Enjoy reading 🙂
What Is the Start/Stop System?
Put simply, the Start/Stop system switches off the engine when the vehicle is stationary.
In cars with a manual gearbox, this happens when the gear lever is in neutral. When the driver is ready to pull away, the engine restarts, usually when the clutch pedal is pressed.
In cars with an automatic gearbox, the system is much easier to use. It activates when the car is stationary and the driver has their foot on the brake pedal. The engine restarts when the accelerator is pressed or, on some models, when the driver releases the brake pedal.
In fact, this is nothing new. Manufacturers have been experimenting with the Start/Stop concept since the 1960s, and the technology first appeared in production cars around the 1980s.
However, it wasn't until 1998, when VW began introducing Start/Stop technology in models such as the Lupo 3L and A2 3L, that it really began to gain ground and become more widespread. Today, you'll find Start/Stop systems in a wide range of vehicles.
Why Is My Car Start Stop System Not Working?
The system has one main purpose: to save fuel in urban traffic. It also brings secondary benefits, such as a reduced environmental impact and lower levels of noise and vibration for drivers and passengers.
*Vibration is a major factor in making you feel tired and reducing your sense of well-being.
However, the system will only operate when certain conditions are met, such as the engine reaching its normal operating temperature. So, if you only use your car for a short trip to the shops and back, you may find that the system doesn't activate at all!
Here's a short list of the conditions that must be met for your Start/Stop system to operate:
- The Start/Stop system has not been switched off manually or disabled using a diagnostic tool.
- The bonnet is fully closed.
- The engine has reached its normal operating temperature.
- The driver's door is closed and the driver's seat belt is fastened.
- The battery is sufficiently charged and in good condition. If the battery is nearing the end of its life, the system automatically enters a protective mode.
- The engine coolant temperature is not too high.
- The engine's exhaust gas temperature is not too high, for example after driving under heavy engine load.
- The outside temperature is not too low.
- The climate control system has reached the selected temperature and can maintain it.
- The DPF is not carrying out a regeneration cycle.
- The vehicle has travelled a certain distance since the system was last activated.
Common Concerns About the Start/Stop System
One of the biggest concerns people have about using Start/Stop is that the car might not restart.
To put your mind at ease and help you use the system with confidence, the fact is that the car's computer can determine whether the engine is likely to restart successfully. If it detects a problem that could prevent this, it won't activate the system. In most cases, you'll see a message such as "Start/Stop system fault".
All cars equipped with a Start/Stop system have a button that allows you to switch it off if you prefer.
The second major concern among drivers and car owners is whether components such as the starter motor and battery wear out faster, or whether engine lubrication and cooling are affected by repeated stopping and starting. The truth is quite the opposite: all these components are designed with the Start/Stop system in mind, with capacity and durability well beyond what is required under normal operating conditions.
The engine's lubrication system has been improved in both design and efficiency. The connecting rod and main bearings have special coatings that retain a substantial amount of oil on their surfaces, even when the engine is switched off. (This is one reason why using aftermarket alternatives during engine repairs isn't always a good idea.) Engine oils and coolants are also specified to withstand this type of operating load, and so on.
In conclusion, I can reassure you that the rumours about your car failing to restart or your starter motor wearing out more quickly are largely fuelled by the fears of owners who don't fully understand how the system works!
If you've found this article useful, don't forget to share it so it can reach more car owners and help them use their vehicles' systems with confidence 🙂
Kris Mladenov