Part number 77366566 fuel water sensor — direct replacement for Fiat Ducato 250, Citroen Relay and Peugeot Boxer (2012 on) Why you need this sensor A fuel water sensor detects the presence of water in diesel fuel before it reaches sensitive components like injectors and pressure pumps. Replacing a worn or faulty sensor restores the vehicle's ability to warn you of water contamination, helping prevent costly fuel system damage and avoid engine performance problems. Key benefits Protects the fuel system: early detection of water prevents injector corrosion and fuel pump failure. Restores warning functionality: replaces a failed or intermittent sensor so dashboard waterinfuel warnings operate correctly. Direct fit for listed models: designed as a replacement for part number 77366566 for Fiat Ducato 250, Citroen Relay and Peugeot Boxer from 2012 onward. Simple maintenance upgrade: swap while replacing the fuel filter to maintain reliable operation of the fuel/water separation system. Key attributes Function: senses water contamination in diesel fuel and transmits a signal to the vehicle's warning circuit. Compatibility: specified fit for Fiat Ducato 250, Citroen Relay, Peugeot Boxer — model year 2012 and later (2012on). Part number: 77366566. Performance: restores accurate waterinfuel detection and dashboard warning when installed as the correct replacement sensor. Fitment: intended as a direct replacement to match original equipment fit and function for the listed vehicles. Typical applications / use cases Routine service replacement: the fuel water sensor when changing the fuel filter or servicing the fuel water separator to ensure continued protection from contaminated diesel. Fault diagnosis and : use this part to a failed waterinfuel sensor that triggers dashboard warnings or causes fault codes related to fuel contamination. Prep for long trips or seasonal storage: install a fresh sensor before long journeys or coldweather storage to reduce the risk of waterrelated fuel system problems. Installation and maintenance notes Intended as a direct replacement for the listed part number and models; installation typically requires access to the fuel filter/water separator assembly. For reliable service, follow vehicle manufacturer instructions and safety precautions for fuel system work. any sealing elements or clips as recommended during service. Compatible with vehicles that require part number 77366566 and listed above. Verify fitment against your vehicle's VIN or consult a parts specialist if uncertain.