Help! E46 is cranking but not starting.

Hello, I have a BMW 320i with the M54B22 engine with a manual transmission and it is my first ever project car. It has been running perfect ever since I got it and started every time without any issues. Until recently and now it won't start at all. I'll write my issue as detailed as possible and hopefully someone will be able to help me and explain to me what could be wrong and what to check as if I was five years old. I have been researching this issue for hours, watched youtube and tried to figure stuff out, but I can't wrap my head around this.

So I drove the car from our house in the countryside back in to the house in the city. While doing this I had an FM receiver in the 12V cigarette port in order for me to listen to my music. I drove home and parked it outside and forgot the FM receiver in the 12V cigarette port.

The next day I drove the car 5 meters up to the driveaway at the house and parked it there, still with the FM receiver in the 12V cigarette port.

A few days later I came back and noticed that the lights inside of the cabin were behaving strangely and whenever I unlocked the car, they turned off, and when I locked the car the lights turned on again. As if the lights inside the cabin were behaving the opposite way they are supposed to. I tried manually switching off the cabin lights and playing a bit, but without any success. I then noticed that I had forgot the FM receiver in the 12V cigarette port and figured that's why my lights were behaving so strangely. I unplugged the FM receiver and locked the car with the cabin lights turned on as I couldn't figure out a way to turn them off while having the car locked. And obviously I need to have the car locked. I didn't have a battery charger available at the moment, but had the possibility to get one the next day so I just let it be.

The very next day I came back and of course the battery had been drained so the car wouldn't start (no cranking), the radio wouldn't work and all of that. I unlocked the car and plugged in a battery charger directly to the battery in the trunk and let it charge up for a few hours. When I came back, the lights inside the cabin were working correctly in correlation to when I locked or unlocked the car. The radio also started working. I unplugged the battery charger and started the car. It started and everything was working fine except for these air vents that I have drawn a red circle around. The defroster where I have drawn a green line was blowing air.

I googled the issue and after some research figured that it would be a component called the final stage resistor which is located under the glove box that's the issue. I thought this because the fans on the defroster were working, so not a problem with the fan itself. I unplugged the old final stage resistor and took it out. Here's how it looks:

I then bought a new final stage resistor, more specifially this one: https://www.autodoc.se/mahle-original/15285510 which is supposed to be the OEM component.

Then a few days later I came back to the car and tried starting it without the final stage resistor plugged in, but without any success. The car wouldn't start and it seemed like I hadn't charged the battery enough and that it was drained again. I then tried to kickstart the car from another car, but without any success. It kept cranking but wasn't starting. Please see this video: E46 320i M54B22 crank no start

I even tried kickstarting it with my friends car, but the same issue. It kept cranking but no start. I started to look inside the engine compartment and noticed that this "F-pipe connector" was disconnected. Please see this image:

I reconnected it and now it is connected and intact. I have even followed the pipes as far as I can see them and they look OK. I tried kickstarting the car again, but still same symptom. I tried disconnecting the mass air flow sensor and kickstarting the car, but still same sympton, it kept cranking but wouldn't start. I have looked on realOEM and it seems like the bottom hose in that "F-pipe connector" leads to the fuel pressure regulator on the fuel filter as far as I have seen on RealOEM. See part 5.

I am not a mechanic, so I don't know what the purpose of this hose is or if it's essential for the car to start? But I figured maybe I will have to try starting the car a few times in order for it to build up preassure and start normaly as if when you change fuel filter, but nope. It wouldn't start. Just kept cranking as if in the video I have posted above.

I have now charged up the battery to its full capacity and plugged in the new final stage resistor and all the fans are working, except for the vents that I had an issue with from the beginning. I figure the car has to be running for these to work properly? Can't find any information regarding this?

Anyways, the car won't start with the new final stage resistor. I am pretty sure this component is not needed at all in order for the car to start, but I was getting kinda desperate so I was just trying to plug everything back in that I had removed. I checked all the fuses under the glove box and they were all OK. I opened the box where the ECU is located and checked the fuses inside of this black box:

All the fuses inside this box looked OK, but just to be sure I used a multimeter and they all showed 0V which is correct.

All the fuses I could think of inside the car were good, so I couldn't understand what the problem is. I checked the battery voltage in the car by clicking the button in the cluster and it showed that I had 13.2 voltage which should be enough with the battery.

When I try to start the car and it is cranking, the big fan in the front is spinning at a low speed and the serpentine belt is spinning at a low speed aswell. I hear a clicking from the hood at this location:

So now my thoughts are that it's not igniting. I tried to remove the air filter box, sprayed some starter fluid and tried starting the car a few times but without any success at all. I have tried to listen if the fuel pump is working by switching the ignition on, but I am not sure if I hear it or not. I have a OBDLink MX+ bluetooth scanner at home that I connect to my phone to read simple codes from different cars. It has worked flawlessly on my friend's Audi A4 B6.

However, when I open any OBD scanning app on my phone it manages to connect to the OBD scanner, but not to the interface/ECU so I am unable to read the codes. I want to know if there's any cylinder missfire, if the crankshaft sensor has given up or whatever, but I can't because it's simply not letting me read the codes. It's a bit frustrating because I am no mechanic and don't know where to look, so an error code would help me a lot.

Here is what is concerning me the most, when I google this issue most people have an issue with just the cranking and the engine not starting, but whenver I turn on the ignition my temperature gauge goes straight to red aswell. Worth mentioning is that I have a full fuel tank. Some people have pointed out that when the temperature gauge goes directly to red when the ignition is turned on, it's an issue with the DME/ECU.

Since I have checked all the fuses in this black box on the image above and the fuses under the glove box, I can't understand why or what may have caused an issue with the ECU as the car has just been battery drained, but has now been recharged again.

Tomorrow I am going to remove the engine cover and check the fuel preassure using this method on the image below to see if there's any fuel preassure.


Can someone please help me identify what the issue could be? I don't believe the final stage resistor and fan issue has anything to do with the car not starting now, but I want to mention it in the thread just in case it has. This whole situation is so odd because all of this happened after a battery drainage and I was pretty certain it was a battery related issue, but now I found that the "F-pipe connector" was not connected and now I really don't know what the issue could be. Should I be concerned that the temperature gauge goes directly to red when turning on the ignition or where should I start looking? It feels like I am shooting in the dark when I am unable to read the codes... The fact that I am unable to read the codes and unable to connect to the ECU/interface worries me even more that it could be an ECU related issue.. What do you guys think I should do? Is there any way to check if the ECU is working correctly?

Please write as if you are writing to a five year old as I am no mechanic.

Thanks in advance for the help and ideas my friends.