A safety switching device for fail-safe disconnecting an external load that has a first pole and a second pole, comprising: a first terminal for receiving a first potential, a second terminal for receiving a second potential, a first switching element between the first terminal and the first pole of the external load, a second switching element between the second terminal and the second pole of the external load, a signal processing unit configured to receive a switch-off signal via an input and to actuate, based on the switch-off signal, the first and second switching element (22, 24), an internal load, and a third switching element configured to connect the internal load in parallel with the external load, wherein a first read-back point is arranged between the first switching element and the first pole, a second read-back point is arranged between the second switching element and the second pole, and a third read-back point is arranged between the third switching element and the internal load, wherein the signal processing unit includes a testing device and a memory in which a first set of error patterns is stored, wherein the testing device is connected to the first, second and third read-back point (42, 44, 50) and is configured to perform a first switching test having at least three test intervals (78, 80, 82; 84) separated in time, wherein the testing device is configured to receive a read-back signal in each test interval (78, 80, 82; 84) at the first, second and third read-back point (42, 44, 50) to generate a first test pattern, wherein the testing device is further configured to match the first test pattern with the first set of error patterns to determine an error. a first terminal for receiving a first potential, a second terminal for receiving a second potential, a first switching element between the first terminal and the first pole of the external load, a second switching element between the second terminal and the second pole of the external load, a signal processing unit configured to receive a switch-off signal via an input and to actuate, based on the switch-off signal, the first and second switching element (22, 24), an internal load, and a third switching element configured to connect the internal load in parallel with the external load, wherein a first read-back point is arranged between the first switching element and the first pole, a second read-back point is arranged between the second switching element and the second pole, and a third read-back point is arranged between the third switching element and the internal load, wherein the signal processing unit includes a testing device and a memory in which a first set of error patterns is stored, wherein the testing device is connected to the first, second and third read-back point (42, 44, 50) and is configured to perform a first switching test having at least three test intervals (78, 80, 82; 84) separated in time, wherein the testing device is configured to receive a read-back signal in each test interval (78, 80, 82; 84) at the first, second and third read-back point (42, 44, 50) to generate a first test pattern, wherein the testing device is further configured to match the first test pattern with the first set of error patterns to determine an error.