Check coolant level message comes on c270cdi - 2001 Mercedes-Benz C-Class

Sensor in the fill tank is probably bad .
LOW COOLANT
The IPC illuminates the LOW COOLANT indicator in the message center when the IPC detects a low coolant level condition from the PCM. The IPC receives a class 2 message from the PCM indicating the coolant level.
Coolant Level Control (If Equipped)
The engine cooling system contains an engine coolant level switch to alert the driver in the event of a coolant loss. The powertrain control module (PCM) sends out a coolant loss signal over the coolant level switch signal circuit. When the engine coolant level switch reads a low coolant level in the fill tank, the switch opens. The message center receives its power from engine wiring harness junction block on the battery positive voltage circuit. Ground is provided by the ground circuits via the body wiring harness junction block and the engine wiring harness junction block. The cluster receives the class 2 message from the PCM indicating Low Coolant and displays the LOW COOLANT LEVEL message on the driver information center (DIC).

Is the fill tank full ?

check the coolant level at the top tank radiator cap
check for an air lock in the cooling system
run the fault codes to check for problem sensors
have a compression test done to check head gasket and cracks

There is no way to reset the light , you probably need a new coolant level sensor !
Coolant Level Sensor Description
The coolant level sensor monitors the coolant level in the cooling system and indicates if the coolant is low. This sensor is located at the base of the radiator surge tank and is not serviceable.
CHECK COOLANT LEVEL (2)
The IPC receives a discrete input from the engine coolant level switch. The engine coolant level switch is normally closed. When the engine coolant is low, the engine coolant level switch opens. When the IPC receives an open signal from the engine coolant level switch, the IPC displays the message on the DIC.
you have to replace this ,Radiator Surge Tank !

check on the side of the resovour there should be a sensor on the side of the tank. i have found these like to stick and leave the check coolant indicator on. check to make sure the coolant is at the full level and gently tap the sensor usually this unsticks it. but to repair it properly ,it will need to be replaced. hope this was helpful!

Hello: You didn't post what year/model car. If its 1996 or newer the coolant level sensor is located in the overflow tank. Sometimes you can tap on the tank near the sensor and it will work. Make sure the sensor is connected, not easy to get access to it. To replace the sensor you will have to replace the tank.

remove the sensor in the coolant bottle and shake it a plastic ball inside sticks

COOLANT LEVEL ON MESSAGE CENTER COMES ON, WHEN CAR REACHES CERTAIN TEMP. GOES AWAY. SERVICE ENGINE SOON ON MESSAGE CENTER REMAINS ON

The coolant sensor and the coolant level sensor are two different sensors. Your message center is showing (coolant sensor bad),not level sensor bad.
The level sensor only monitors the amount of coolant in the container
The coolant sensor senses the degrees of the coolant, which turns on the electric cooling fans. Change the coolant sensor, and the problem should go away.

you may be low on coolant either the overflow bottle or in the radiator both have sensors on them

the floater inside the coolant gets stuck t wont overheat it is just a pain to see the light all the time