[Pumper]

Hi,

I have a problem. My 2007 320D just stopped working for no apparent reason, here's a short timeline:

- was not driving it for a couple of weeks
- was standing outside in the cold (up to -12C at night)
- had to move the car out of the way yesterday (a few meters only) and noticed some squealing noise but just thought it might be because of the cold and just needs to get warm
- wanted to go out today (minutes ago) and was warming up the car a bit before driving
- looked for the source of squealing sound and found out that it was coming from the back of the car (exhaust maybe) - most noticeable from under the car closest to rear right wheel
- after a few minutes the far just shut off (some warning sign of the car with arrows to front and back came up and then just ! mark)
- can no longer press the break pedal (a few milimeters maybe) to start the car normally (auto box)
- car starts and shuts off immediately

Battery is new, glow plugs new, etc. Car was starting up without issues before this. Any idea what might be wrong?

The only fault code I was not able to get rid of was:
46D3 - Internal ECU 4 / Internal Control Unit 4 / Control unit internal 4

[kiel_dafo_kenyg_as]

frozen diesel (paraffin) in tank?
squealing sound may come from the fuel pump.

[Pumper]

Yeah, most likely it's the fuel pump dying (checked some videos on YT and they sound very similar to mine).

Will wait for a bit warmer weather to have a closer look.

[kiel_dafo_kenyg_as]

Good luck!

[CMB Arthur]

Mate,

i hate to be a bad news unclu but internal error means usually that there is a phisically problem with yours ECU, it could be caused by dump or colt weld etc.

Try reflash the ECU then recode it if it wont help than you need new ECU with proper Immo decoding

[gazzcav]

pull the plastic cover off ecu housing and see if there is any water in there

[Pumper]

Dry as a desert. Most likely it's a software issue.

BTW, my fuel pump was ok after all. Towed the car into a heated garage, kept it for 24hours there and it started up without issues. The fuel froze in mild cold. Filled up with winter diesel, replaced the fuel filter and the car runs fine now (funny thing is, the parent's Volvo V70 actually had a broken down fuel pump a week later).

Will be getting petrol car next time, lol.

[Pumper]

So I finally managed to take the car for some proper diagnostics with dealer tools.

The guy reinstalled the ECU software, but this did not the 46d3 fault (remap is gone now, though). So I guess it's a hardware issue, not software. Not gonna pay ~1/5 of the car's value for a new ECU, so will be driving with a faulty one. The only solution would be to open up the unit and see what might be wrong with it.

Anyone have any experience with mechanical repairs on ECUs? Did that solve the problems you were having?