Hopefully this will help one of you!
Just hit 34,000 on 2019 Cummins, driving home, check engine light came on, followed by “reduced engine power warning”, pulled over, scanned OBDII, and got code P00B7 (coolant level too low).
1) checked coolant level and it was at the correct level
2) pulled the wiring harness plug off of the coolant level sensor on the bottom of the overflow tank
3) used scanner to clear code P00B7 so “reduced engine power warning” and check engine light goes away and you can drive home like normal….ish! No issues while driving
4) got home and the check engine light comes on again, code P2559 (coolant level sensor plug disconnected). Not a big deal, because this code will not trip the “reduced engine power warning”
5) called the dealer, they ordered a new overflow tank/sensor for me, will be delivered in a week
6) in the mean time I didn’t want that pesky check engine light on so I did what the technicians are trained to do at the dealership to get your truck back on the road until the coolant tank comes in (temporary fix)
7) disconnect and remove the passenger side battery (disconnecting both batteries terminals is a safe practice to follow)
8) disconnect the harness plug from the coolant level sensor at the bottom of the coolant tank again
9) now, push up on the bottom of the sensor ever so slightly, and at the same time, rotate the sensor 1/4 of a turn clockwise (the sensors plug end should be facing the front bumper this point), then pull straight down and the sensor will come out, it will be loose and just sitting there against the metal bracket below it (you will not be able to take out the entire sensor, it will just rest there)
NO COOLANT WILL COME OUT REMOVING THIS SENSOR, SO DON’T WORRY ABOUT THAT
10) rotate the sensor back 1/4 of a turn counter clockwise and re-install the harness plug back on the coolant level sensor and just let the sensor sit on the metal bracket below.
11) install passenger side battery, connect battery terminals, and use scanner to clear the check engine light code P2559
12) you should no longer have any CEL’s on the dash at this point, and they shouldn’t reappear while you are waiting for your new coolant overflow tank to come in.