The validation of the work of computational algorithms operating within the positioning system services under unusual measuring conditions is an important part of the entire system. Particularly noteworthy conditions are failures of reference stations forming the examined station network. The article evaluates the operation of the algorithm implemented to the POZGEO sub-service of the ASG-EUPOS system in the event of failure of reference stations used in the standard determination of the coordinates of the selected spatial point. The research material consisted of 117 days of continuous determination of the position of the selected spatial point using 1 hour of GPS static observations. Reports on the procedure of determining the position in the post-processing mode in POZGEO sub-service of static satellite observations were used to simulate the reduction of the number of tie vectors in coordinates’ determination method. The resistance of the automatic post-processing algorithm to failure of parts from the standard reference stations used was assessed.