Constant Indication of Low Coolant

[redefine.m3]

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[NorthernDancer]

https://www.realoem.com/bmw/enUS/sho...diagId=17_0322

item 3, coolant level sensor. Might be a place to start. BTW, most experts say to keep coolant level at MIN mark, not Max mark. More allowance for expansion as our expansion tanks are prone to leak.

https://www.pelicanparts.com/More_In...=0&SVSVSI=4380
For some strange reason Pelican Parts identify the sensor as being for headlight washer tank; maybe same sensor is used in both places.

[nachob]

Originally Posted by redefine.e82

Hi,

Recently I've been getting the low coolant symbol showing whenever I start or turn off my car. I've taken a look in my coolant reservoir in the morning and it's sitting right on the max level. I've also went ahead and filled a bit more coolant just to be safe but the indicator still shows. There's no leaks. What are the possibilities that could be causing this? Is this a common issue among 1 series?

Thanks!

Did you take the purge screw almost out and top off the reservoir with the engine running and inside heater set to high with blower on low? I had a similar problem in my E46 but after I did these steps it went away. I was able to add about 1/2 to 3/4 liter of coolant. It looked full when sitting cold but in order to fully fill you have to have the purge screw almost out to let air bubbles escape and have the heater on so it circulates through the entire system and the engine on so the pump can kick on and open the thermostat etc. There is also an electric pump purging procedure you can try. It's online something like face east, pump the throttle several times while say Abra Cadabra then turning ignition on while shifting butt cheeks side to side and closing your eyes.

I would try that before buying a new sensor. Make sure you use 50/50 diluted BMW blue coolant. Let us know if you have tried that or if it helps after trying.

[redefine.m3]

I'll look more into that and give that a try. Thanks for explaining that!

[nachob]

Originally Posted by redefine.e82

I'll look more into that and give that a try. Thanks for explaining that!

Here is a video on purging the water pump. You can try this after filling up correctly. It only takes a little bit of missing coolant for it to throw the coolant light and don't forget to put it back in. I saw a guy forget to put it back in.

[WDE82]

The E82 system is quite a bit different than the E46. E46 was super sensitive to bleeding properly and also the ET would pop on a lot of cars. I've always attributed most of those to overfilling. The E82 has no such weaknesses I'm aware of but it's definitely good practice to keep the coolant low-mid rather than high for expansion.

If you don't have any cooling issues then I would not suspect you have an issue with air in the system.

Note that the coolant level sensor can be replaced without draining any coolant.

[nachob]

Originally Posted by WDE82

The E82 system is quite a bit different than the E46. E46 was super sensitive to bleeding properly and also the ET would pop on a lot of cars. I've always attributed most of those to overfilling. The E82 has no such weaknesses I'm aware of but it's definitely good practice to keep the coolant low-mid rather than high for expansion.

If you don't have any cooling issues then I would not suspect you have an issue with air in the system.

Note that the coolant level sensor can be replaced without draining any coolant.

I agree I have e46 and e82 was just using it as an example of how if not bled correctly can appear full . I also think that before replacing the sensor you should still be sure it's bled correctly . It costs nothing to do . Then if you replace the sensor you will still have to make sure you use the bleed screw. It's there for a reason in both platforms.

[WDE82]

Originally Posted by nachob

I agree I have e46 and e82 was just using it as an example of how if not bled correctly can appear full . I also think that before replacing the sensor you should still be sure it's bled correctly . It costs nothing to do . Then if you replace the sensor you will still have to make sure you use the bleed screw. It's there for a reason in both platforms.

Agreed bleed attempt is free and he has coolant on hand.

[Tommm]

Sensor on the E46 for the expansion tank is the same as the sensor for the washer fluid.