Start-stop system not working: what does it mean?

You stop at the traffic lights and the engine keeps running. That is often not a fault: the car is protecting the battery. Below you can read when that is normal, when the battery is the cause and why the start-stop sometimes stays off after a new battery.

By the team at Autobedrijf Willemsbrug, RDW-approved APK (MOT) test station since 1979 · Updated 6 November 2026

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The short answer

The start-stop system only switches the engine off when the car is sure it will start again afterwards. According to battery maker Varta, the battery management system switches the start-stop off when the battery charge is low, and also in cold or hot weather, with a cold engine, a fan running hard or a door open. If the start-stop no longer works after a new battery, Varta says the battery may not have been registered with the car properly, or the wrong type may have been fitted. According to the ANWB, the Dutch motoring organisation, a car with start-stop needs an AGM or EFB battery. If the start-stop stays off for weeks in mild weather with normal journeys, have the battery tested.

Battery service at Autobedrijf Willemsbrug: we test the battery, the charging system and the starter motor first, and only replace what is needed. A new battery suits your car (AGM or EFB with start-stop) and we register it with the on-board computer if your car requires that. We tell you the price in advance based on your registration number. Call +31 10 479 00 00. You bring the car and we call you when it is ready. A loan bike is free while one is available. Saturdays too. Our team speaks English. More about our battery service

Why does the start-stop not switch the engine off?

Because the car first checks whether it can safely start again afterwards. According to Varta, the system only switches the engine off when all the conditions for a reliable restart are met. A sensor on the battery keeps track of the charge and the condition. The battery management system (BMS) is the part of the on-board computer that monitors the battery and controls the charging current.

Varta lists these reasons why the start-stop does not work. Most of them are normal and not a fault:

Situation Why the engine keeps running A fault?
The battery charge is low Why the engine keeps runningThe BMS switches off the start-stop so the engine is sure to start again A fault?No, but have the battery tested if it continues
It is very cold or very hot outside Why the engine keeps runningThe outside temperature is outside the system’s range A fault?No
The engine is still cold or very hot Why the engine keeps runningThe engine temperature is outside the range A fault?No
The fan or the air con draws a lot of power Why the engine keeps runningThe battery would have to supply too much power A fault?No
Seat belt unfastened, door or bonnet open Why the engine keeps runningA safety condition, separate from the battery A fault?No
Parking assistance active or a steep slope Why the engine keeps runningA safety condition, separate from the battery A fault?No
After a new battery Why the engine keeps runningThe battery has not been registered properly or is the wrong type A fault?Yes, have it checked
The battery is at the end of its life Why the engine keeps runningThe energy management switches off the start-stop A fault?Yes, have the battery tested

Source: Varta, Start-stop does not work and Start-stop myths.

Why does the start-stop work less in winter and on short trips?

Because the battery then has less charge and the car uses more power. According to the ANWB, cold weather puts more strain on a battery. On short trips the battery has to supply power for starting again and again, and gets too little time to recharge. In winter the fan, the rear window heater and the seat heating are also on more often.

The battery management system sees this and keeps the engine running to spare the battery. Varta advises having the battery charge checked, especially in cold weather or after a lot of short trips. If the start-stop works again after a longer drive on a mild day, a low charge was the cause.

Why has the start-stop stopped working after a new battery?

Usually because the new battery has not been registered properly or does not suit the car. Varta mentions these causes:

  • Not registered: the car has not recorded the replacement properly and does not recognise the battery as new.
  • Wrong data: if the technology or the capacity of the battery has not been entered correctly, the BMS cannot use the right charging strategy.
  • Wrong type: a battery with a different technology has been fitted, which can only handle a small number of charge cycles.

A mechanic registers the battery (also called battery coding) with diagnostic equipment. According to the ANWB, the learning process is complete when the start-stop, the climate control, the rear window heater and the electric power steering work normally again. How that works and which cars need it is explained in registering a new battery with the on-board computer.

Which battery does a car with start-stop need?

An AGM or EFB battery. According to the ANWB, all cars with a start-stop system are fitted with an AGM or EFB battery. According to Varta, an EFB battery (Enhanced Flooded Battery) is a more powerful version of the standard starter battery. According to Varta, an AGM battery (Absorbent Glass Mat) is strong and durable, and is mainly found in cars with an advanced start-stop system and brake energy recovery.

Varta writes that standard starter batteries cannot cope with the heavy load of the stop phases. Bosch gives this rule: replace an AGM with an AGM and an EFB with an EFB. According to Varta, switching from EFB to AGM can be sensible. We fit the same type, or the type the manufacturer allows. You can read more about types, lifespan and cost in our car battery replacement guide.

When is it a fault, and can I still drive?

You can carry on driving: without start-stop the car drives normally. The engine then keeps running when you stop. There are, however, signs that something more is going on:

  • The start-stop stays off for weeks, even on mild days and after longer drives.
  • The dashboard shows a warning about the start-stop or the battery.
  • The engine starts more slowly in the morning than you are used to.
  • The start-stop has not worked since the battery was replaced.
  • The battery is more than a few years old. According to the ANWB, a battery lasts around three to six years.
Rule of thumb: if only the start-stop is not working, you can drive and make an appointment. If the car also starts with difficulty, have the battery tested quickly, because there is a good chance the car will soon fail to start. If a red battery warning light comes on while you drive, stop. According to the ANWB, you must pull over when a warning light is red.

How we find the cause

We first test whether it really is the battery, before we replace anything. When the start-stop is not working, we do the following:

  1. Diagnostics: with diagnostic equipment we read out the fault codes and the data from the battery management system.
  2. Battery test: with a battery tester we measure the charge and the condition.
  3. Type check: we check whether the battery fitted is the right type and the right capacity for your car.
  4. Charging system test: we check whether the alternator charges the battery properly.
  5. Registration: if the battery has not been registered properly, or if we fit a new one, we register it with the on-board computer if your car requires that.

We tell you the price in advance, as one amount based on your registration number (kenteken), and we only replace parts with your approval. You can read more about the test on our page about car battery testing in Rotterdam.

Frequently asked questions

Is it a problem if the start-stop is not working?

No. The car drives normally without start-stop. Usually the car switches the system off for a while to spare the battery. If it stays off for weeks, have the battery tested.

Can I switch off the start-stop myself?

Yes. On many cars you can do that with a button on the dashboard. On most cars the system switches back on the next time you start the car. What applies to your car is in the owner’s manual.

Can I fit a standard battery in a car with start-stop?

No. According to Varta, standard starter batteries cannot cope with the load of the stop phases. According to the ANWB, cars with start-stop have an AGM or EFB battery. The wrong type deteriorates faster and the start-stop may stay off.

Will the start-stop work again if I charge the battery?

Yes, if a low charge was the cause. According to Varta, the battery management system switches the start-stop off when the charge is low. If the battery is worn out, charging only helps for a short time and you need a new battery.

Does every new battery need to be registered?

No. That depends on the car. According to the ANWB, on many modern cars the battery has to be registered in the energy management system. Bosch mentions BMW, Volkswagen, Audi, Peugeot and Fiat, among others. We look it up for your car based on the registration number.

Why does the air con get weaker when the engine stops at the lights?

According to Varta, the start-stop can remain available while the air con automatically cools less. On many cars the air con compressor is driven by the engine, so the air con cools less during the stop. If the fan draws a lot of power, Varta says the car switches the start-stop off instead.

Can a worn battery switch off the start-stop?

Yes. According to Varta, the car’s energy management switches off the start-stop when the battery is at the end of its life. A battery tester shows whether that is the case.

Start-stop no longer working?

Call +31 10 479 00 00 with your registration number. We first test the battery and the charging system, and we tell you the cost in advance.

You will find us at Boterdiep 11 in Rotterdam-IJsselmonde, close to Stadion Feijenoord (De Kuip). We work by appointment. For a quick question or check you can walk in without an appointment.

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