Boat owners with Volvo Penta engines, listen up! This is a brand-new temperature sensor (also called a sending unit) that fits a bunch of popular Volvo Penta engines – the 3.0, 4.3, 5.0, and 5.7 liter models. The part number is 3850397, and it's listed as x3 in the details (might refer to quantity or a specific variation). It's aftermarket, not OEM, but it's designed to do the same job: monitoring your engine's coolant temperature and sending that info to your gauge or warning system. This sensor is crucial – if your temp gauge is acting wonky, reading too high or too low, or not working at all, this little guy might be the culprit. It comes new in its packaging, just like you'd find in a parts store (though sometimes in simple non-retail packaging). Swapping it out is usually a simple job: locate the old sender (often near the thermostat housing), unscrew it, and screw this one in. Just remember to use a little thread sealant and be careful not to overtighten. Keeping your engine temperature monitored is key to avoiding overheating and big repair bills. This sensor helps you catch problems early. Whether you're prepping for the season or fixing a sudden gauge failure, having a reliable sensor on hand is smart boating. Always check your specific engine model to confirm fit, but for these common Volvo Penta blocks, this sensor should get you back on the water with accurate temps.