A pressure monitoring system for a combustion engine includes, but is not limited to of combustion chambers and pressure sensors associated to at least some of the combustion chambers. A multiplexer has inputs connected to at least a first one and a second one of the pressure sensors. A non-zero phase shift exists between the operating cycles of first and second ones of the combustion chambers associated to the first and second pressure sensors. A controller controls the multiplexer to output data from the first pressure sensor while the first combustion chamber is in a predetermined portion of its operating cycle and pressure data from the second pressure sensor while the second combustion chamber is in the predetermined portion of its operating cycle.