VDO Heavy Duty Normally Closed Single Circuit 4 PSI Pressure Switch

The VDO Heavy Duty Normally Closed Single Circuit 4 PSI Pressure Switch (MPN 230-504) is a precision marine electrical component engineered for applications requiring reliable pressure-activated switching in saltwater and freshwater environments. Built with a normally closed single circuit design rated at 4 PSI maximum pressure, this switch delivers the dependable on-demand switching that marine systems demand, from bilge pump activation to hydraulic pressure monitoring on larger vessels.

The switch operates across a 6–24V range, making it compatible with both standard 12V marine electrical systems and higher-voltage setups common on larger boats and commercial applications. Silver alloy contacts provide superior corrosion resistance compared to base-metal alternatives—a critical consideration in the salt-air environment where marine pressure switches face constant oxidation stress. The two-terminal configuration and #8-32 connection accept standard marine wiring harnesses without requiring custom adapters. With a floating ground design, the switch integrates seamlessly into existing electrical architectures without ground-loop complications.

This normally closed pressure switch is essential for fishermen and boaters running automated systems that activate at low pressure thresholds—bilge pump activation when water accumulates, fuel pressure monitoring in inboard engines, and hydraulic trim/tilt systems on outboards and sterndrives. Weekend anglers maintaining single-engine center consoles and serious offshore crews operating diesel twins both rely on VDO pressure switches to trigger alerts and system activation without constant manual monitoring. The 4 PSI rating suits low-pressure applications where margin and sensitivity matter more than heavy-duty industrial service.

VDO is an OEM supplier to major marine engine manufacturers, and OEM-spec replacements like this switch carry the same engineering standards used in factory installations. When a pressure switch fails mid-season, having an exact-match replacement on hand prevents system downtime that could strand you miles offshore. Sold as an individual unit with no bulk packaging required.