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This guide outlines specific repair steps—ranging from connector inspection to spool cleaning—to address five common malfunctions of hydraulic solenoid valves, such as the indicator light turning on while the valve fails to operate.

Loose connector: If the indicator light is on but the valve is not working, first check for a loose connection; repeated plugging/unplugging and vibration can cause contact wear, so simply replace the connector.

Unstable voltage: If excessive connections or the aftermarket installation of solenoid valves leads to a voltage mismatch, the light may turn on, but the voltage is insufficient to actuate the spool; the power supply must be adjusted.

Stuck spool: Use a small hex key to push the spool; a lack of spring-back or rough movement indicates it is stuck. Try pushing it back and forth to dislodge debris; if this fails, disassemble and clean the unit.

Burnt coil: A burnt odor upon disassembly indicates a burnt-out coil; simply replace it with a new one.

Overtightened screws: Overtightening screws during replacement can deform and jam the valve body (particularly in domestic valve assemblies), so care must be taken to apply the correct tightening force.

These methods can resolve 99% of routine hydraulic solenoid valve malfunctions.