Why is my car’s start-stop system not working?

• Your car’s stop-start system cuts costs and emissions by turning off the engine at standstills.
• Battery issues, cold weather, unfastened seat belts, open bonnet can affect its function.
• Don’t expect stop-start to work when parking or reversing due to frequent gear changes.

Cutting back on fuel consumption is a big priority for everyone at the moment. Vehicle stop-start systems have proven to be a helpful way to reduce fuel usage as well as emissions. However, when your car’s start system isn’t working as expected, you may be wondering how to get to the bottom of the problem. 

In this article, we’ll guide you through what stop-start systems are, how they work, and how you can troubleshoot issues with yours. 

What is start-stop?

A start-stop system, or a stop-start system, is in-built vehicle technology designed to switch your car engine off when it’s not in use, for example when the vehicle is not moving in a traffic jam or at traffic lights. This stopping and starting happens automatically and is used to prevent your engine from idling and from using unnecessary fuel. Stop-start systems, therefore, are designed to improve air quality and reduce fuel consumption, saving the planet and your pocket.  

How the start-stop system works

Start-stop systems can pick up when your car is stationary by sensing when the brake pedal is in use and the gearbox in neutral. The vehicle’s onboard computer will then cut off the engine in response. It will sense the release of the brake and clutch or accelerator pedal being used, to restart the engine. 

The driver can choose to turn start-stop off completely by pressing the corresponding button on the car’s instrument panel. If this is not immediately obvious the button will also be outlined in the manufacturer’s handbook. 

Issues which may affect your car’s stop-start

If your start-stop system is experiencing problems, take a look at our troubleshooting suggestions for the possible causes. 

• Cold weather: In cold temperatures (around 3’c or below), stop-start may not kick in when the engine is cold. This is partly to protect your battery, especially if you have a heater and wipers also on, but also to allow your engine to warm up appropriately. Your car will adjust its behaviour to protect its core components – and this can include halting your stop-start system. 

• You don’t have the right battery or the battery is low: For a start-stop system to work, it requires a battery that is powerful enough to withstand the constant starting and stopping. If your battery is not powerful enough, or simply does not have enough juice to operate in this way, then this could cause your car to inhibit the ability of the start-stop system. 

• If you are making a manoeuvre: The car will recognise that during a manoeuvre, such as parking or reversing, for example, a lot of changing gear will naturally be taking place, and therefore the stop-start system would likely be a hindrance. If the car senses that you are making a manoeuvre, by registering the wheel is turned at a severe angle or reverse gear is engaged, it will cut out the stop-start function. 

• Seatbelts are unfastened: Ensure that everyone in the car has their seatbelts on, and then try again to see if this corrects the problem. 

• The bonnet is not closed properly: For safety reasons, if a car bonnet is not shut properly, this could cut out the start-stop system. Get out when it is safe to do so and check the bonnet is completely closed. 

Still not sure? It could be that you require a diagnostic check of your vehicle to find the cause of the failure – and to provide an effective solution.  

With over 50 years’ experience as the go-to car tyre suppliers in Central England, our talented technicians are here to help with your vehicle’s needs – from exhausts and clutches to brakes & batteries. Simply give us a call at one of our 35+ auto centres across the region.