The existence of hardware induced phase biases might influence the accuracy in precise positioning if not handled properly. This is extra problematic if the biases are dependent on the satellite tracked, as these biases no longer will be common between the satellites, and thus will not be absorbed by the receiver clock term of the positioning solution. In this paper, we carried out two studies to investigate whether there exists a satellite dependency of the relative phase biases. Even though small in size, satellite dependent variations were found in both cases. In the first case, relative receiver phase biases were studied, while relative phase biases between signals (e.g. between carrier phases from C/A-code and P-code tracking) were investigated in the second case. The biases in the first case had a size of 0.8 mm between the satellites with the largest and smallest values, and additionally showed temporal variations that were consistent over time. The corresponding sizes of the biases second case were 2 mm and 3.5 mm for GPS L1 and L2 respectively, and no temporal variations were found.