[Drifter2090]

Hey guys, my little sisters 2008 BMW 328i always shows the low coolant light when it's coolant is always at the max level.

Things I've tried:
New expansion tank level sensor
Full coolant flush and bleed

Is there another coolant sensor other than the one on the expansion tank? Could it be the expansion tanks floater itself?

Thanks!

[drymite]

Originally Posted by Drifter2090

Hey guys, my little sisters 2008 BMW 328i always shows the low coolant light when it's coolant is always at the max level.

Things I've tried:
New expansion tank level sensor
Full coolant flush and bleed

Is there another coolant sensor other than the one on the expansion tank? Could it be the expansion tanks floater itself?

Thanks!

I had the same issue on my 2006 330i. Mine was the coolant reservoir sensor.. i changed it worked for 3 months then failed again. So i just ignored the coolant light knowing the coolant was good..

[e90yyc]

You might have noticed when replacing the sensor that no coolant actually leaks out when it’s removed.

The level sensor relies on a “magnetic float” inside the tank to determine the coolant level. The sensor itself does not touch the coolant.

It’s likely there was nothing wrong with the sensor to begin with. Rather, the float inside the tank may be stuck or fucked up in some other way.

Easiest route would be to replace the expansion tank. If you wanted to remove the tank and try to jimmy the float loose inside that’s another option. Wish I could explain this a bit better but you get the gist.

[Drifter2090]

Thanks, I understand what you're saying. Wasn't sure how it worked!

I'll give a new tank a try, thank you

[3DIRTY8]

I am now experiencing this same issue after doing my Valve Cover Gasket.

- I swapped out the tank and the light is still there
- I’ve bled the system multiple times
- I jumped the tank’s sensor wiring harness to see if there was a break in the line, light still glowing
- I changed the Water pump & thermostat appx 10k miles ago
- No codes on INPA

I did notice that the light will eventually go away after running the car a couple minutes past operating temps.

[Drifter2090]

Originally Posted by 3DIRTY8

I am now experiencing this same issue after doing my Valve Cover Gasket.

- I swapped out the tank and the light is still there
- I’ve bled the system multiple times
- I jumped the tank’s sensor wiring harness to see if there was a break in the line, light still glowing

I did notice that the light will eventually go away after running the car a couple minutes past operating temps.

I haven't had a chance to replace the tank yet since it's still winter here, but thats same issue with this 328.

[marvinstockman]

Funny, 1998 M3 had the same problem, which I just ignored, and now it is my son's problem since I gave him the car. That said, I want the back!

[3DIRTY8]

Before I jump the connector wires as a permanent solution anybody have any ideas on what to do

[3DIRTY8]

So I figured it out. BUY OEM TANK+SENSOR.

I went through 2 Dorman (Autozone w/ Liftime - I figured it just holds fluid so why not save a couple bucks) within 2 weeks for a Low coolant light that would not go away.

I finally got fed up and went to the dealer to compare the two. The cheap reservoirs are 90% of time missing a metal ring that goes around the the float sensor. Thus not creating the magnetized connection the sensor needs.

[Drifter2090]

Originally Posted by 3DIRTY8

So I figured it out. BUY OEM TANK+SENSOR.

I went through 2 Dorman (Autozone w/ Liftime - I figured it just holds fluid so why not save a couple bucks) within 2 weeks for a Low coolant light that would not go away.

I finally got fed up and went to the dealer to compare the two. The cheap reservoirs are 90% of time missing a metal ring that goes around the the float sensor. Thus not creating the magnetized connection the sensor needs.

Thanks! I'll order a oem replacement

[Drifter2090]

New tank fixed the issue, thanks!

(used a uro parts tank)

[thalastdon1985]

Just to add to this this, I've bought a few cars that had Dorman tanks installed and all had a low coolant light that was rectified with an OEM or Behr brand tank. Seems like the sensor in the Dorman unit isn't correctly made.

[335ibeam]

Help!
So my boyfriends car is a 2009 bmw 328i xdrive sedan and we replaced the coolant thermostat and we were trying to bleed it. When we tried to bleed it the water pump does not turn on nor make the noise. We checked the fuse and it was perfectly fine. Do we replace the water pump?