Provided is a print engine controller for an inkjet printhead with a plurality of nozzle arrangements operatively actuated by thermal actuators. The controller has controller circuitry with an open actuator test circuit to test each respective actuator. The controller circuitry includes an open actuator test input, a column enable input and a row enable input, as well as a drive transistor operatively linking said thermal actuator to a power supply. The circuitry also includes a bleed transistor arranged in parallel with the thermal actuator, and a sense transistor operatively linking an output of the drive transistor and inputs of the thermal actuator and bleed transistor to a sensing node. The controller circuitry is configured so that when only the column enable and row enable inputs are activated the bleed and sense transistors are deactivated and the drive transistor is activated to link the thermal actuator to the power supply.