Methods and apparatus for conducting in – service testing of a pneumatic signal amplifier are disclosed . In response to a test initiation signal , a processor of a valve controller operatively coupled to the pneumatic signal amplifier supplies a pressurized control fluid to an inlet of the pneumatic c signal amplifier . The processor determines a first pressure value corresponding to an inlet pressure of the pressurized control fluid at the inlet of the pneumatic signal amplifier , and further determines a second pressure value correspond ing to an outlet pressure of the pressurized control fluid at an outlet of the pneumatic signal amplifier . The processor determines a ratio value between the first and second pressure values and determines whether the ratio value satisfies a threshold . In response to determining that the ratio value satisfies the threshold , the processor generates a notification indicating that the pneumatic signal amplifier is functional.