An algorithm is presented for constructing complete asphaltene PT phase diagrams. The algorithm works with any equation of state capable of providing consistent fugacity coefficients and appropriate derivatives for gas, oil, and asphaltene-rich phases. SRK, PC-SAFT, and CPA were successfully applied. The algorithm has been validated against multiphase PT flash calculations, and the results are further shown to agree with asphaltene simulation results in the open literature. Construction of the asphaltene PT phase diagram is fast and robust even in near-critical regions. Examples are shown illustrating the multitude of possible appearances of an asphaltene PT phase diagram. The algorithm has been modified to take an injection gas amount as specification, which allows for construction of asphaltene Px phase diagrams showing the response of phase boundaries to gas injection. Usage of the algorithm to get a full overview of the behavior of the asphaltene precipitation of the fluid is demonstrated.