Car won't start in the cold? Causes and tips

Why doesn't the car start in the cold?

The reason why the car does not start in winter is often due to the battery or the engine oil. The reason for this is that both components are particularly sensitive to cold. This is what happens as soon as it gets cold:

• Low battery: On cold days, the starter battery is less powerful. This is because the cold slows down the reaction that converts the chemical energy of differently charged elements into electrical energy. Therefore, even with a fully charged battery, there may not be enough voltage for starting. If it is cold, the battery also discharges faster. As a rule, the alternator charges the battery every time you drive. Cold can disrupt this process, so that the battery is not charged or charged very slowly – and therefore discharges more quickly.
  
  
• Viscous engine oil: The colder it is, the more viscous the engine oil becomes. As a result, it flows worse and does not supply the engine block evenly. As a result, the starter, which starts the engine via a gearwheel, is not sufficiently lubricated and has difficulty getting it going. The engine can even be permanently damaged as a result.
  
  
• Iced fuel lines: In rare cases, there is moisture in the fuel lines, which can freeze on cold days, causing a fuel blockage. This leads to the engine not starting due to a lack of supply.
  
  
• Frozen Fuel: The diesel starts badly in winter? In diesel vehicles, diesel itself can "gel", i.e. freeze. It then flows more slowly and takes longer to supply the engine. That's why it doesn't start at the first ignition. Because diesel flocculates from temperatures of minus seven degrees, you should fill up with winter diesel in the cold season. Thanks to additives, it is frost-proof down to minus 20 degrees.
  
  
• Clogged carburetor: If the car is more than 20 years old, the carburetor can also be the cause of the car not starting in the cold, even though the battery is okay – i.e. charged. This is because carburettors are particularly susceptible to icing. If the nozzles of the carburettor are clogged, moisture collects there that does not evaporate. At low temperatures, ice can form and put the carburetor and engine out of service. This does not happen with modern cars – they are usually built without a carburetor.

Basically, a weak car battery is more likely than icy fuel lines or a clogged carburetor. That's why the first thing to check is the battery if the car doesn't start in winter.

Car won't start in winter: What can I do?

In winter, it is important to conserve the battery, as it is less powerful in cooler temperatures. Therefore, it is best to proceed as follows.

Starting the car in winter: The most important things summarized:

1. Turn off the radio, lights or seat heating to save energy and save the battery.
2. Turn the ignition key only briefly.
3. If the car starts, let the engine warm up.
4. If none of this works, get a jump start – either from another car or a power bank for vehicles.
5. If the battery is not the cause, check the oil level and top up with winterproof oil if necessary.

If the car does not start at all in the cold, first switch off everything that consumes additional energy, such as the radio, the lights or the seat heating. Then turn the ignition key briefly – because long "organizing", i.e. starting while the engine does not ignite, only puts a strain on the battery. If the car starts, let the engine warm up and turn off all the equipment for a few minutes. Otherwise, the battery can die again and the engine will stop again. Tip: A warm engine also helps against fogged up car windows. This is because it warms the windows and drives away condensation, especially on the windshield – for a clear view.

The car still doesn't start in the cold? Then start-up assistance may be necessary. To do this, the battery is bypassed with the help of a jumper cable that connects the car battery to that of another car. If no other driver can help out at this moment, the best thing to do is to call an automobile club such as the ADAC or ACE. If you are a member, the breakdown assistance even comes free of charge - but basically every driver is helped. Do you have a power bank for vehicles? Then you give yourself a jump start with her and are not dependent on outside help.

If the cause is not the battery, the first thing to do is to check the oil level and refill it if necessary. Important: Be sure to use winter-proof engine oil. You can tell whether an engine oil is winter-proof by the SAE class on the label. It describes the viscosity of the oil as a function of temperature – for example, whether the oil is liquid at a temperature of minus 12 degrees. This is what the different designations mean:

• 0W: highest winter resistance, oil liquid down to minus 30 degrees
• 5W: Oil liquid down to minus 25 degrees
• 15W: Oil liquid down to minus 10 degrees
• 25W: Oil liquid down to minus five degrees

You can find out which engine oil is suitable for your car in the service booklet or ask the manufacturer. As a rule, engine oils with SAE class 0W are recommended by manufacturers in Germany.

How can I prevent my car from starting in winter?

To ensure that the car starts even in the cold, it is best to store it in a garage. There it is not directly exposed to the weather. As a result, the car itself cools down less than compared to vehicles parked outside. On the other hand, it is in the dry, so less moisture collects in the car. This makes the fuel lines less susceptible to frost. A garage parking space is particularly advisable if the car is not to be driven for several months, for example because it is only the second car.

A regular check of the engine oil shows whether there is enough oil. To be on the safe side, you can also store suitable, winter-proof oil in the car and are thus prepared for emergencies. Also practical in the event that the car does not start despite precautions: a power bank or start cable in the car. It is important to know that a car battery cannot be charged indefinitely. Therefore, depending on the age of the battery, it may make sense to buy a new one directly. As a rule, this is necessary after four years.

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