BMW E46: Crank No Start. What Might Be the Reason?

Are you having a problem starting your BMW E46? Are the ignition dashboard lights on and the car not starting? How can you fix it? Maybe you had this problem a long time ago and it resurfaced without notice. It's totally fine and you should worry less because this article will show you how to fix the problem. 

Crank-no-start problems highlights

• Level of urgency:High
• Can you drive?Obviously, no
• DIY inspection:Possible but complicated
• DIY repair:Mostly,impossible
• Price for repair:$350 - $800
• Common Reasons:No spark, no fuel, no air, battery issues, starter problems, electronics
• Ways to fix:Inspect units that may cause this problem one by one

Why Your E46 Won't Start

Fuel

The first thing to check is if your car doesn't start. You need to be sure there is no leakage somewhere that drained up all your fuel overnight.

Air

Having a massive vacuum leak can cause the car not to start. It's necessary to check if there is a lot of air getting into your system. Having a clogged air filter can always do the trick too.

Ignition fuse

Whenever your car doesn't start despite the crank sound, it is necessary to check the fuses. The ignition fuse may be the problem. Here is a brief below on how to fix this problem.

• Locate the fuse box 

The fuse box for the BMW E46 is located at the driver's side under the hood, close to the DME, and right below the windshield. It has a plastic covering.

• Open the box

The fuse box is carefully tightened with some neatly fitted screws and you will need a screwdriver to loosen the screws to help you open the box.

Once you are done unscrewing, the cover becomes easy and can be lifted without much effort from its position.

• Locate the engine management fuse box 

This is a small fuse bank that contains five 20 AMP fuses and they are separated by slits so you can easily see them.

• Remove the small fuse box gently

The fuse box is tight (just a little bit) and you may have to lift it gently. Without removing it, you won't be able to test each fuse to detect the bad one.

• Test each fuse with a multimeter

Once you have been able to remove the small box from its position, you can turn it upside down to display the iron bars of the fuse. Of course, you can hold it from the top but just to make it easy for you.

If any fuse is blown, that means it is burnt and needs a replacement immediately.

• How to Detect the Ignition Fuse

The ignition fuse is locked in the middle of the small fuse bank in your E46

• How to replace the bad fuse

The small fuse box is closed on both ends of the slits. Lift the lock on both ends then slide down the top covering to the side so you can see the fuses. Pull the bad fuse out and replace it with the new fuse. Then slide the covering back to fit and lock on both ends.

Now, you can fix the small box back to the large fuse box and cover it.

• Start the Car

After replacing the bad fuse and covering the fuse box, you can now test the car to see if it is working. We are sure your car should work fine now.

• Here is a case scenario of this problem

A BMW E46 owner once changed his car battery and found out the car didn't start, he checked the fuse and also confirmed they were all fine. On the second check, it was discovered that one of the fuses was bad. Would you like to know what that fuse was? Yes, you guessed right. The ignition fuse.

It is necessary to cross-check the fuses again if the car still doesn't start. Sometimes, they may not be detected on the first inspection.

Fuel Pump

Another reason why your car refuses to start is your fuel pump not supplying much pressure. Whenever you start the car, you can hear the fuel pump kick at the rear for about 2 seconds. The car needs this pressure to start and not getting enough amount of it can affect the car from starting. The following fixes have been provided to solve this problem when it occurs.

• Locate the fuel pump

This is under the rear seat of the car behind the driver's seat.

• Try adding pressure to the pump

There is a Schrader valve on the fuel rail, take off the fuel injector cover from the engine. You will need to crank your car now to apply pressure then take a flat head screwdriver and press on the valve. This should cause a lot of gas to start shooting out. If there is no sign of gas, then the fuel pump is the issue. You should try fixing the fuel pump.

• Fuel Pump Fuse

To check the pump fuse, you need to find out where it is located. You can check your glove box where you will find a little key that will show you where the fuse is. Every car should have this key but if yours doesn't a little research online can do it.

• Fuel Pump Relay

This is a little bit harder to find. All you need to do is take out the glove box, then unlatch the fuse panel so you can have a clear view of the fuse pump relay which is on top of it.

Crank Shaft Position Sensor

This is located behind the starter on the body of the engine. If the sensor is bad, it can stop the car from starting.

• How to know if the sensor is okay

Crankshaft position sensors give square wave signals when they are working well and this should be your focus when checking. They are known for having up-and-down switching square wave signals. You can check if your sensor is working by using a multimeter to show the signal.

• How to connect the meter to the sensor

Place the black meter wire tip together with the negative wire of the sensor and also place the red wire tip on the sensor's signal wire. The voltage usually switches between 0 to 5 volts for a good sensor. If the sensor is dead, the signal won't show at all.

You can also get a BMW scanner from Amazon which won't cost you much and also save you time and a lot of money going to the mechanic. A simple check can help you detect the fault on time. Be sure to buy one from a verified or reliable brand.

Coils

There is a chance that your coils may not be working. You need to be sure that your ignition is receiving 12 volts from your coils. Sometimes, if the ignition fuse is blown the coils get disconnected and cause the car not to start.

There is also a chance that your ignition coils may be bad. It is very rare for all 6 coils to go bad because of how they are connected.

Spark Plug

You could have a bad spark plug too and won't know. It's necessary to have a spare plug in your garage or somewhere safe and easily accessible so you can replace the bad plug as fast as possible.

Exhaust

If the exhaust is plugged up then it's a bad sign for your car. It can stop it from having enough air.

• How to check if your exhaust is plugged up

You need to use the O2 sensor which works like a compression gauge with a rubber tip that you can stick into the hole and then crank the car to test the backpressure. You shouldn't be getting back pressure of up to 3 pounds. If this happens, then you have an issue with your exhaust.

We hope this article helped you fix the issue. And we also hope that your marvelous BMW E46 will never let you down again.