The sensor only detects a buildup of water in the filter canister. Water in diesel is not uncommon, just the degree that varies. Where you get your fuel is something to consider. If you just want to turn off the warning light just pull the connector on bottom of filter and/or remove the sensor. But, then you won't get the warning and eventually
BOSCH Sensor, fuel pressure High Pressure Side. Fuel Mixture Formation: Common Rail (CR) Supplementary Article/Info 2: High Pressure Side. Condition: Brand new. Show OEM numbers. £ 136,88**. £ 97,18. incl. 20% VAT, excl. delivery costs. Add to basket.gt4DJ. 895 704 925 539 484 181 805 161