Siemens Resistor AGK25

This resistor, Siemens AGK25, is a sensor component intended for Siemens controllers and control modules. It is used in electronic circuits of engineering systems, particularly in boiler and burner control circuits, where it provides a fixed resistance for signal conditioning or as a reference. The component is designed for automation, control, and HVAC equipment, ensuring stable processing of electrical signals. It fits Siemens controllers and Siemens control modules.

Selection of such a resistor depends on its nominal resistance, tolerance, and power rating—all must match the component being replaced and the control board's requirements. Before ordering, confirm the resistor's specifications, as the part designation identifies a specific variant in the manufacturer's range. The replacement must have the same electrical parameters and be compatible with the circuit layout. If the board uses a temperature sensing input, the fixed resistance value is used for reference or signal conditioning, so the rated value must be exact.

Resistors of this kind can drift from their nominal value or fail open. When that happens, the control may misread sensor signals, leading to unstable modulation, incorrect temperature readings, or a lockout condition. To diagnose, measure the resistor's value with a multimeter after disconnecting power and compare it to the board's design specification.