Coolant Temp Sensor - Commander 950

The Holley Coolant Temp Sensor - Commander 950 (part number 534-10) is an electric temperature sending unit designed for precision coolant temperature monitoring in fuel-injected engine management systems. This digital sensor features a 3/8-inch NPT brass connection and integrates seamlessly with Holley Pro-Jection fuel injection controllers and compatible aftermarket ECUs. By providing real-time coolant temperature data, this sensor enables accurate fuel mixture tuning, engine protection logic, and diagnostic feedback essential to modern performance engine builds.

The 3/8-inch NPT thread pattern is a standard metric for coolant passages in most automotive heads and blocks, allowing direct installation without adapter fittings in many applications. As an electric sender rather than a mechanical gauge, the Commander 950 removes analog signal noise and delivers consistent digital output to the Pro-Jection ECU, improving idle quality, cold-start enrichment mapping, and engine protection thresholds. The brass wetted components resist corrosion in ethylene glycol coolant environments, critical for reliability in extended storage or high-performance cooling systems running extended heat cycles. Weighing 0.16 lbs with compact dimensions (3.6 x 2.55 x 3.75 inches), installation clearance is minimal in tight engine bay layouts.

This sender is engineered for builders and tuners integrating Holley fuel injection into street rods, restomod vehicles, and performance swaps where factory coolant temperature inputs are unavailable or incompatible. Engine builders rely on digital coolant temp feedback to calibrate spark advance curves, lean burn tables, and fan relay logic—tasks that demand repeatable, noise-free sensor signals. The Coolant Temp Sensor - Commander 950 is essential equipment for anyone running Holley Pro-Jection systems and needing OEM-quality thermal monitoring without proprietary connector dependencies.