If you’re like the rest of us, you probably don’t have a set of tools lying around in your car’s trunk. So you have nothing to fall back on when your car stops in the middle of the road, leaving you stranded. Your BMW won’t start, and you have no idea how to fix it or get home.
If your BMW runs with a push-button start mode, the key will do absolutely nothing to make your car respond. Push-button start systems are the next step in automobile evolution, but not everyone is familiar with how the mechanism functions. Please continue reading to know more about the possible reasons your BMW won’t start and how to fix them.
We have prepared a list of tips and tricks that can help you when your vehicle refuses to start. Of course, none of these techniques aim to fix the problem at the root, but maybe one of them will help you get your BMW began to in desperate times. But make sure to head over to the mechanics at your earliest convenience.
- Push Button Ignition
- BMW Push-Button Start
- Possible Reasons
- Car Malfunctioning
What Is A Push Button Ignition?
All push-button start cars, even the ones made by BMW, feature a keyless ignition system. The fob has to be inside the BMW for the start button to be pushed for the engine to start. The fob establishes a connection with the BMW’s computer system and lets the driver start the engine without a key rotating the ignition. In simple words, the fob transmits low-frequency signals to your BMW.
Every fob produces a unique ID signal that only connects with the vehicle assigned to it. The car receiver will pick up the signal and answer by delivering power to the motor.
BMW Push-Button Start
Keyless entry was more or less a premium addition to luxury vehicles up until the middle of the 1990s. However, many BMWs from that era still require a physical key insertion to be unlocked and then pushed into ignition mode to start the engine.
Statistics published by the NHTSA (National Highway Traffic Administration) said that only 5,000 cars had been made with a push-button start in 2002. After 11 years, Ward’s Auto said that the number had reached 4.4 million and was rising.
However, BMW always strives to be at the top of the game with its innovative additions. They evolved their keys again as technological improvements allowed them to. Currently, they have done a full revamp of their key fob.
The brand new seven and i8 series models come with a completely interactive control device that allows you to transcend the borders of a physical instrument signaling the engine to start.
The push-button start technology is convenient and has resulted in fewer car thefts. There are, however, certain cons of having a BMW powered by a push-button start.
One downside is that if the BMW doesn’t start, the key fob might be one of the causes. Let’s look at some of the reasons why your BMW refuses to start, particularly if it has a push-button start engine.
The starting symptoms of a BMW can vary. Below are some of the more common symptoms you will notice when your BMW won’t start.
- The car doesn’t start when all lights are off/dead
- The engine doesn’t start when START is pushed
- No reaction after the key is inserted
- The engine makes a clicking noise, but it won’t start
- The engine doesn’t start after a battery change
- It doesn’t start in cold temperatures
- EML light on, but BMW doesn’t start
- Lights flashing, but BMW is off
- The key symbol is displayed on the dashboard
Possible Reasons Behind Why Your BMW Won’t Start:
Now let’s talk about the plethora of reasons your BMW may not start.
- Weak fuel pump
- Poor ignition coil
- Worn spark plugs
- PCM Coolant Sensor/Engine Temperature Sensor
- Faulty starter
- Damaged key
- Electrical problems
- Bad fuel relay or pump
- Faulty key fob battery
In addition, there can be a conventional electrical issue stopping the BMW from starting, like:
1. Faulty Starter Motor
Your engine will not start if your starting motor fails or is damaged. If you believe the starter seems to be the source of the car’s ignition problem, try jumping it directly. If the engine still doesn’t start after that, you might have to change the starting motor or get a new module, relay, or solenoid.
The BMW’s battery is connected to the starting motor. A dead battery is a typical reason for BMW starter motor failure. You might replace the battery with a fresh one in this scenario.
2. A Discharged Or Dead Battery
If the key is functioning, but your engine does not start, you may have a drained or empty car battery. As stated before, the most common reason for your BMW not starting is a dead battery. If the battery is not sufficiently charged, the engine will not start, nor will any electrical component be used.
You may jumpstart your vehicle to determine whether the problem is with the battery. If the car starts, it is most probable that the battery is dying or the alternator is malfunctioning.
3. The Issue In The Starter Circuit
There might be a minor problem with the starting circuit or the car battery’s connections. First, inspect the solenoid. If it is functional, it will click when the contacts shut. If it doesn’t function, there might be a problem with the ignition switch and its terminals, the solenoid, or the wiring.
A few of these issues are general for every BMW model, but some appear specifically for vehicles with push-button start motors.
4. Weak Battery
You have to check the battery next. If the dashboard or lights cannot power up, there is an issue with the battery. Some of the symptoms include:
- Lights won’t turn on
- There isn’t any noise
- No clicking sounds
- No dashboard light
Your BMW will click or crank with the lights on, but there will not be enough power to start the engine. The issue might still be with the car’s battery if the radio works and the lights come on. You should still examine the battery. The battery might have adequate power to operate electronics like the radio and lights but not enough power to turn the engine over.
This kind of problem typically appears with a battery over seven years old or is infected by a parasitic draw fault.
4.5. Possible Solutions
- Trickle charge battery
- Jumpstart battery
Always use the jumpstart connectors under the hood, not those that connect directly to the battery. You can also use a trickle charger for the charging phase. This process needs anywhere between 5 to 24 hours, but many mechanics prefer this over rejuvenating a discharged battery.
When the battery is charged, the car should start without any problems – unless there is a damaged cell in the battery. If the signs return after a few days, chances are, the battery has become incapable of holding charge. A parasitic drain may be doing the same thing to your new battery. Alternatively, the battery may simply be at the end of its service life and require a replacement.
Consider replacing the battery if it’s been working for more than seven years. Learn how to replace car batteries here.
5. Inspect Relays And Fuses
A bad relay or perhaps a blown fuse may be the reasons behind your BMW not working. Fortunately, checking the relays on a BMW is quite easy. The fuse can be removed and visually inspected. A digital multimeter can also be used to check them.
You can find the BMW fuse boxes on these locations:
- Trunk area
- Under or by the side of the dashboard
- Engine bay
This is a list of all the fuses that have been removed and checked:
- Fuel pump relay/fuse
- Starter relay/fuse
- Security fuse/Immobilizer
- Alarm system
- Ignition switch control module
- DDE/DME/Engine electronics fuse
- Main relay
- Engine control module (ECM)
- Central locking system
- Ignition switch control module
- Engine management
Ensure to inspect the relays, particularly for the fuel pump and starter. You can change identical replays or just swap them.
6. Check Battery Safety Terminal BST
A fault in the Battery Safety Terminal can answer why a BMW won’t start. The component can detonate if the vehicle was in an accident, hit a curb, got rear-ended, or a battery replacement didn’t go right.
The biggest signs of a faulty BST cable would be the radio, accessories, and BMW lights working but the car not starting. The BST can be found at the tail of the positive cable attached to the positive post. When the vehicle is in a collision, the igniter and gas inside can explode.
So, if you get into an accident, the component will dismantle the alternator and starter. You will get a fault code too in the airbag control module as the airbag light comes on.
Find the battery inside the trunk if you want to confirm whether the BST cable is poor.
To verify if the BST cable is bad, locate the battery in the trunk. Disconnect the red cable from the battery positive clamp/BST. Know the BST detonated if the cable could be removed easily. This is when the cable has to be replaced. The cable can be manually pushed back into the component or reconnected properly, and your car should start.
Remember that the airbag light can stay illuminated after this issue and will require a BMW scanner for the reset.
You can buy a new BST repair cable for your BMW online and do the replacement yourself. Local dealers will also sell you the cable for a much higher price. Expect the repair to set you back anywhere between $500 and $900. Just by DIY-ing this repair, you can save hundreds of dollars. But don’t try this if you don’t have some sort of experience handling car bits.
7. Weak/Dead Key Fob Battery
The keyless engine cannot start until it senses the presence of a key inside your BMW. If you have the key fob in the BMW, but the engine doesn’t start, the battery in the key may be dead. A key fob with a depleted battery is deemed worthless as the vehicle’s system cannot detect the fob. You have not only a dead key but also a BMW that won’t start.
However, there is one way around this. You might fail to unlock your BMW this way, but it can still be accessed manually.
To unlock the door:
- Find the key release button at the fob’s base and press and hold down on it.
- To open the doors, extract the internal key blade. It can be used as a standard key.
- If the keyhole cannot be located, search for the little hole on the handle’s bottom.
- Enter the key blade inside this hole and remove the trim panel. You should then be able to find the keyhole and enter your vehicle.
For a manual start, you can:
- Slide the key fob inside the ignition slot.
- Hold the fob close to the markings on the steering column side.
- Position the key fob on the button (start engine) and press down.
The tips stated above will help give you access to your BMW again, but we recommend replacing the key fob battery as soon as possible. Depending on the fob, you have to replace the battery and use a new CR2032 or CR2450.
If you choose to replace the key totally, it may cost you a little. The starting price for a key fob for BMW is $300. Newer and more advanced BMW models need fey fobs that are more expensive.
8. Defective Push Button Start System
Who doesn’t love technology? Many motorists prefer push-button start technology. However, like with any technological device, things might go wrong. They tend to malfunction now and then. If your BMW won’t start and you are sure the key fob’s battery hasn’t died yet, the criminal may be the push-button start mechanism.
Below are some of the reasons a push-button start mechanism has gone bad and is hindering the regular start of your BMW:
- Faulty brake pedal position switch or clutch. This can also happen due to a malfunction with the switch wiring harness.
- Bad push button or problem within the push button wiring harness.
- Faulty steering interlock release module.
- Bad Neutral/Park safety switch.
9. Fluctuating Fuel Pressure
If your BMW cranks without starting, you should examine the fuel pressure. Fairly straightforward, the test should take no more than 15 minutes. Lift the engine cover to reveal a Schrader valve at the tip of the fuel line. Most BMWs feature a Schrader valve; however, a few models will not.
Attach the port and the fuel pressure gauge and monitor it whenever you turn on the ignition or attempt to power your car.
10. Bad Ignition Coils Or Spark Plugs
Inspect the coils and spark plugs if your BMW won’t start or starts but then dies. Common indicators of spark plug issues include poor fuel efficiency, loss of power, failure to start BMW, and engine misfires.
If you changed the spark plugs, but your BMW doesn’t work anymore, double-check that all the wiring harnesses are correctly connected. Do not switch the wires connecting the ignition coils. Each wire ignition coil wire must be connected to the ignition coil it was disconnected from in the first place.
11. Bad Starter
Check the starter for symptoms of malfunction too. A defective starter will not allow the engine to turn over.
BMW Won’t Start: Troubleshooting
If your BMW turns on without starting, the first thing to do is inspect the fuel pressure, compression, and spark.
How To Read BMW Fault Codes?
A BMW can have all the lights on, and the radio and dashboard are coming on but still not starting. This is when you can read the fault codes. Fault codes can be stored in 1 or multiple modules.
A conventional OBD-II scanner (Level 1) cannot retrieve specific trouble codes for BMWs. You need a BMW scanner to read and clear these codes from different modules.
Perform a thorough system scan or a health report using your BMW scanner. A powerful scanner will enable you to run an automatic scan of all modules. When the scan is finished, you will be given a report containing the BMW trouble codes. Keep an eye out for any codes with the status CURRENT or PRESENT.
These will have to be dealt with. Codes that display HISTORY (based on the scanner) may be easily removed.
BMW Won’t Start: Car Malfunctioning Under Specific Conditions
BMW Won’t Restart After Fuel Has Run Out
Yes, any automobile will stop running when the gas runs out, but the issue here is that even after adding gas, your BMW won’t start. Blame this on the formation of air pockets in the fuel lines.
BMW Won’t Start In Cold Weather
When parked outside in the cold, your BMW might not start in some cases. A typical general indication would be the engine slowly turning over before starting. You may generally start the BMW by revving the engine numerous times or waiting for it to warm up, neither of which is ideal.
Firstly, you should look at the battery. This issue might be caused by a battery nearing the end of its service life. Because battery performance declines as the temperature drops, it may be more difficult to start the vehicle if it is chilly outdoors.
BMW Won’t Start Post-Accident
A BMW may not restart after an accident because of the Positive Cable Battery Safety Terminal, or BST. The BST disconnects the positive wire cable when it senses that the vehicle was in an impact or accident.
During a crash, the battery is removed to reduce the risk of explosion, shocks, and possible electrical shorts.
It usually shoots when the airbags deploy. However, it can fire on its own without the airbags deploying. By reconnecting the cable, you can skip the BST. It is suggested that the cable be replaced as soon as possible.
The airbag module will also store a fault code, and the airbag light will remain illuminated. With a BMW-specific scanner, restore the airbag light after repairing or installing a new BMW BST cable.
BMW Won’t Start Even With A Jump Box
What to do when your BMW doesn’t start despite connecting the jumper box? This can happen due to either one of the two reasons:
- There is low-quality or poor contact with the jumper cables
- The battery is short or discharged, stopping the starter from getting enough power to turn the engine over.
Connect the 2nd source of power to your BMW to start it. A lithium jump box can boost the starter’s power. An alternate method is to connect the helper car jumper wires for at least 15 minutes. This might be harmful if the battery has run out of power. It can overheat and, in rare situations, explode.
BMW Cranks But Doesn’t Start
So, your BMW cranks but doesn’t start? The reason will be one of the following:
- The engine isn’t getting enough fuel
- Low compression
- Poor spark plugs
- A poor DME issue
- The defective crankshaft position sensor
Perform a fuel pressure test to start the engine. Find the port on top of the engine on the fuel rail and connect it to a pressure gauge. The reading should be close to 60 PSI. Afterward, you can use a spark tester to check the spark. It will need you to take off the engine cover along with at least one spark plug. Last but not least, examine for compression.
BMW Won’t Start But Clicks
This issue is frequently caused by a faulty battery or an exploded Battery Safety Terminal. Attempt to jumpstart the BMW or replace the battery.
Usually, if your BMW won’t start, the cause can be narrowed down to an issue with the fuel system, ignition system, or engine. Once you decide that the system is dealing with an issue, diagnosing the bad component will be significantly easier.
These tools have been tried and tested by our team, they are ideal for fixing your car at home.