8 Reasons Why Your BMW Z4 Won’t Start

BMW Z4 is a rear-wheel-drive sports car and it is indeed an excellent car, but you need to understand that it can also break down just like other machines. 

Every car is a machine that could easily develop a fault, especially if there is no proper maintenance. However, you don’t have to panic when you experience a breakdown because it can always be fixed. 

There are several reasons why your Z4 can break down and they include; a weak battery, an empty fuel tank, and a poor battery connection. Aside from these reasons, there are still other reasons why your Bmwz4 won’t start, and I will be sharing them with you in this article, along with possible techniques you can apply to fix these issues.

BMW Z4 won't start

1. The Battery is Weak/Dead

Your BMW Z4 is equipped with a six-cell, 12-volt lead-acid battery. Each of these cells consists of lead plates in a lattice and is completely covered with sulphuric acid. Therefore, when it is weak or dead, you will not be able to start your car because your Z4 engine can not run without a battery.

Its battery’s lifespan depends on how you handle the battery and also the weather conditions. Although normally, it should last for 3-4years. 

If your BMW z4 refuses to start, you can perform a 12V battery test to verify if the problem is actually from the battery before jump-starting it. If the battery is dead.

BMW Z4 won't start - weak battery

Troubleshooting And Fixing A BMW Z4 Battery

12V Battery Test

This test helps you measure the voltage between the poles and find out the condition of the battery. This test is performed with a voltmeter. 

Usually, a healthy car battery should be 12.6 volts, but if it is above 14 or below 11.5 volts, then you might need to replace it.

When you want to measure the voltage of the battery with a voltmeter, you need to make sure that the vehicle has been sitting for at least an hour after a long ride to enable you to get the accurate “resting voltage”. 

BMW Z4 won't start - battery test

Jump Start Your BMWZ4

When you perform the test and you discover that the reason for the breakdown is a dead battery, you can easily jump-start it using jumper cables and a healthy battery from another vehicle. To jump-start your z4, you need to ensure that your vehicle donor is parked close to yours so that you can be able to perform the following steps: 

  • Identify the negative and positive terminals of your car battery and ensure that it is clean.
  • With the jumper cables, connect the red cable to your battery’s positive terminal.
  • Hook the other red cable to the positive terminal of the donor vehicle.
  • Connect the black cable to the negative terminal of the healthy battery.
  • Connect the last cable to the bare metal in your car’s engine bay.
  • When you have properly connected the cables, you can start the donor vehicle and also your z4.
  • Then carefully remove the cables from both batteries, starting from the last cable to the first, and keep your engine running for at least 10 minutes.
BMW Z4 won't start - jump-start-battery

2. The Battery is Poorly Connected

A car battery is the power source of every vehicle, and it converts chemical energy into electrical energy to enable the electrical parts of a car to function properly. Therefore, if your battery cables are not connected to the right terminals, then your car won’t start.

To connect your battery properly, you have to connect the positive battery terminal first and then connect the negative battery terminal. To disconnect your battery appropriately, you do it in the reverse order—disconnect the negative battery terminal first and then the positive terminal.

BMW Z4 won't start - poor battery connection

Read: What Does The C and H Mean in a Car

3. The Fuel Filter is Clogged

Your fuel filter can become blocked with so much dirt, and this will cause the filter to become clogged. When this happens, your engine will no longer function the way it is designed to function and your z4 will fail to start. If this is the case, the only way to fix a clogged fuel filter will be by replacing the filter.

BMW Z4 won't start - clogged fuel filter

4. The Starter is Broken

A broken starter is another common issue that can contribute to your car’s breakdown. The purpose of a starter is to start your engine and get your vehicle moving, but when it’s broken, you won’t be able to enjoy a ride in your car.

Some of the ways to identify if you have a broken starter are that you will always hear a clicking sound when you turn on the engine of your car and also that your engine will not turn over. When this happens, you will need to replace the broken starter with a better one.

BMW Z4 won't start - broken starter

Read: Clunking Noise When Braking

5. The Alternator has Failed

An alternator is a generator that generates energy. If your car’s alternator fails, it will be unable to produce energy and the battery will not charge. 

Even if you replace the battery, it will always run out and the engine will not start because the alternator is what generates the energy. Your car alternator can fail as a result of how long you have used it. And the only option for such an issue is a replacement.

BMW Z4 won't start - failed alternator

6. The Fuel Pump has Failed

If a car’s engine occasionally breaks down, starting the car becomes difficult. The engine performance declines, and this results in the fuel pump developing faults.

If your fuel pump fails, the engine will not start. The pump generally guarantees that the correct amount of fuel is transferred from the tank to the engine’s injection system under sufficient pressure. So, if your fuel pump is faulty, you won’t know when you are out of fuel and it can prevent your BMW Z4 from starting.

BMW Z4 won't start - failed fuel pump

7. There’s a Rodent Damage

Another reason why your BMW Z4 won’t start is rodent damage. The creatures creep beneath the car and feed on the cables and wires. This can affect your car and cause it to not start, especially if there’s been major damage. You can take it to a car workshop to change the damaged cables.

BMW Z4 won't start - rodent attack

Read: Drivetrain Malfunction BMW

8. The Key Fob Battery is Weak

This is another common reason why your Elandra might not start. If you have a weak key fob battery, you might not be able to start your car using the start/stop button on your car.

If you have a model of Z4 that only has a key fob with a start/stop button and no place to insert a key, you can use the back or end of the dead key fob to push the start button while pressing the brake.

BMW Z4 won't start - weak key fob battery


When you discover that the issue is the battery and you want to change it, make sure you replace it with an Absorbent Glass Mat (AGM) battery. Because they are best suited for cars like your BMW Z4 than the original batteries. Also, it is necessary to always take your vehicle to a car workshop for proper checkups and repairs.