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Discussion Starter · #1 ·
Hey guys,

So i replaced my expansion tank, water pump, and thermostat last week. However, after everything was replaced i am still getting a coolant light warning and it won't go off. I replaced the sensor when i installed the expansion tank. The coolant is full and I'm not sure whats going on with it... Any help would be appreciated!

Thanks,
Michael
 

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Look and feel, did you plug the sensor plug till it clicked and secured itself? You also have to bleed it well, then ride a while, let it cool over night or a couple of hours(one hour with hood popped), then check your coolant level. Should be low a couple times. Just top it off, repeat, until you're good to go.
 

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Discussion Starter · #7 ·
What brand tank?
The brand is Meyle. I was in a pinch and needed my car and i wasn't able to order it online. The only place that had it was Napa... I did bleed it but ill try it again and see if that will work. I double checked the sensor but i will check again. Do you think i should just order a BMW expansion tank and replace this one...
 

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I have heard of this happening with aftermarket tanks. That very may well be it, but try the above suggestions first. The connection is simply a reed contact: the float within the tank contains a magnet, which pushes two small pieces of metal away from each other in the sensor, creating an open circuit, which registers to the ECU that the coolant is low. Also make sure your contacts are not corroded. Unplug/replug it, and try some dielectric grease.

I would personally order a Genuine BMW tank, or go with an OEM tank; however, Meyle is reputable and I would trust their tank. They've done a lot of good in the E46 world.
 

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You can check the reed switch sensor with a small magnet and a continuity checker. I think when you put the magnet near it, it makes contact. Could be the opposite. Either way, it does the opposite when the magnet is near it. Or just swap it with the one in your windshield washer tank. They're the same, i believe.
 

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+1 swap with tank sensor.
 
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