A control system for monitoring a filter (2a, 2b) in a subsea control module of an underwater hydrocarbon well, wherein an input of the filter is connected to a hydraulic fluid source (1a, 1b) to receive a hydraulic fluid, and wherein the filter (2a, 2b) is configured to filter the hydraulic fluid, the control system comprising: an upstream pressure transducer (10a, 10b) disposed upstream of the filter (2a, 2b) and configured to sense an upstream pressure of the hydraulic fluid; a downstream pressure transducer (7a, 7b, 8) disposed downstream of the filter (2a, 2b) and configured to sense a downstream pressure of the hydraulic fluid; a subsea electronics module (11, 12) coupled to the upstream pressure transducer (10a, 10b) and the downstream pressure transducer (7a, 7b, 8), and wherein the subsea electronics module is configured to determine average pressure differential values at different instances based on the upstream pressure and the downstream pressure; characterized in a master control station located on a top-side facility and coupled to the subsea electronics module (11, 12), said master control station being configured to: receive the average pressure differential values from the subsea electronics module (11, 12); determine a rate of change of the average pressure differential based on the average pressure differential values; extrapolate the rate of change of the average pressure differential to obtain an extrapolated average pressure differential; predict a filter maintenance due time based on the extrapolated average pressure differential, the rate of change of the average pressure differential, and a target maintenance pressure differential; and generate an indication of the predicted filter maintenance due time for an operator of the underwater hydrocarbon well. an upstream pressure transducer (10a, 10b) disposed upstream of the filter (2a, 2b) and configured to sense an upstream pressure of the hydraulic fluid; a downstream pressure transducer (7a, 7b, 8) disposed downstream of the filter (2a, 2b) and configured to sense a downstream pressure of the hydraulic fluid; a subsea electronics module (11, 12) coupled to the upstream pressure transducer (10a, 10b) and the downstream pressure transducer (7a, 7b, 8), and wherein the subsea electronics module is configured to determine average pressure differential values at different instances based on the upstream pressure and the downstream pressure; characterized in a master control station located on a top-side facility and coupled to the subsea electronics module (11, 12), said master control station being configured to: receive the average pressure differential values from the subsea electronics module (11, 12); determine a rate of change of the average pressure differential based on the average pressure differential values; extrapolate the rate of change of the average pressure differential to obtain an extrapolated average pressure differential; predict a filter maintenance due time based on the extrapolated average pressure differential, the rate of change of the average pressure differential, and a target maintenance pressure differential; and generate an indication of the predicted filter maintenance due time for an operator of the underwater hydrocarbon well. receive the average pressure differential values from the subsea electronics module (11, 12); determine a rate of change of the average pressure differential based on the average pressure differential values; extrapolate the rate of change of the average pressure differential to obtain an extrapolated average pressure differential; predict a filter maintenance due time based on the extrapolated average pressure differential, the rate of change of the average pressure differential, and a target maintenance pressure differential; and generate an indication of the predicted filter maintenance due time for an operator of the underwater hydrocarbon well.