DIY Coolant Level Switch/Sensor Replacement

[Genes1s]

I've search this but couldn't find it so I thought I'd document my process. This is how I've done it, others might be difference.

1. Disconnect the Negative terminal. Make sure that the lead is in secured spot to prevent it moving around away from the battery negative post and other electrical systems. Some says no need to, some says better do it than sorry. Took me 2 minutes to do it. Would you take a look at the battery...dang..I was shocked the first time seeing this battery with so many wires that I thought I have a hybrid system for a sec....

2. Fold the rear seat flat, just incase, you accidently close the trunk. The latch is inside the trunk on the top section of the rear deck. Again, why can't BMW do the latch inside cabin like normal cars do?? I don't understand why new car is this way, but I'd prefer a key hole.
3. Drain the batter juice out by turning the headlights on for 10-15 seconds then switching off. Always a good habit to get rid of stored energy.
4. Remove 2 #10 screws holding the coolant reservoir tank.

5. Lift the tank upward to release it from the rubber grommet. Its best to have another set of hand to do this, but its do-able solo. Be very careful not to stretch the coolant hoses risking a damage on the connections.

6. U can access the wiring harness now and disconnect it from the sensor.
7. Twist the sensor 90 degree to direction of the front of the car. If you are not sure, get a flash light and look where the slot for the plastic boss will disengage. No fluid WILL come out.

8. Get your new sensor.

9. Install the sensor in the reverse direction. Make sure you twist it back to locking position.
10. Reconnect the negative battery terminal. Secure the #10 nut battery terminal. Make sure it is tight but don't gorilla tight them.
11. Start the car and verify that everything is OK.
12. Reset your time and you are done.


It took me 15 minutes from start to finish including taking pictures. Pretty straight forward.

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Excellent, always appreciate a good write-up. Thanks!

Agree with #2, fold seats down so you can get into the trunk if needed. Learned that the hard way.