Volvo All Engines (2013 Emissions) Fault Code: P256000 PID: EMS Engine Coolant Level Low

Voltage from the engine control module (ECM) is applied to the engine coolant level (ECL) switch when the ignition switch is in the ON position. When the reservoir runs low, the float will be lowered on the coolant level sensor. The signal to the ECM will indicate low coolant.
If the engine control module (ECM) detects that the coolant level switch has experienced a power loss or that the level can not be detected, the ECM will set a diagnostic trouble code (DTC) and derate the engine to avoid engine damage.

Conditions for diagnostic trouble code (DTC):
1) Coolant Critically low level

Observable symptoms
1) Power loss
2) High derate with potentional engine shutdown

Probable cause
1) Low coolant level
2) The sensor float is stuck
3) Connector
4) Wiring harness
5) Engine Coolant Level (ECL) Sensor
6) Engine control module (ECM)