A magnetic sensor circuit includes a plurality of magnetic sensors having bias input and bias output terminals and first and second measurement terminals. The circuit includes a diagnostic sensor having bias input and bias output terminals and first and second measurement terminals. The circuit includes a first multiplexer configured to selectively couple a current source to the bias input terminals of the magnetic sensors or to the bias input terminal of the diagnostic sensor and includes a second multiplexer configured to selectively couple the bias output terminals of the magnetic sensors or the bias output terminal of the diagnostic sensor to a first terminal of a switch. The circuit includes a third multiplexer configured to selectively couple the measurement terminals of the magnetic sensors or the measurement terminals of the diagnostic sensor to differential input terminals of an amplifier.