Water temperature switch 1/2''x14 NPTF 2 Pin

The engine cold start temperature switch sends a signal to the fuel pump to switch on the KKSB cold start solenoid valve when the water temperature is below 60ºC. The KKSB then activates the fuel pump solenoid, the timing and the cold start system.
Failure of the engine cold start temperature switch will result in the fuel pump not receiving 12 volts when the coolant/block temperature is below 60ºC.
Part number 1001257, located on the left side of the cylinder head, next to the fuel injection pump. It controls the cold start device of the fuel injection pump (KSB).
Engine runs poorly when cold due to defective engine water temperature switch.
Engine runs rough, flutters and emits white smoke on cold start.
Check the engine water temperature switch (part number 504264463). A defective switch prevents voltage from being applied to the cold start solenoid switch of the fuel injection pump. The result is erratic engine running and excessive smoke until the engine reaches normal operating temperature.
If the engine coolant temperature is less than approx. 53 degrees C, check for continuity at the terminals of the engine water temperature switch. If there is no continuity, replace the engine water temperature switch. If there is continuity at the switch terminals, check the connector terminals for looseness and corrosion that could result in an open circuit or high resistance in the connection.

Tighten the water temperature switch to the correct torque 35Nm.
+60°