Fejlfunktion

Fejlfunktion is a Swedish term used to describe a malfunctioning function within a system, device, or software. It refers to a function that does not perform as intended due to defects, wear, external conditions, or software bugs. In practice, it denotes the observable behavior that differs from the expected or specified behavior, which can range from minor glitches to critical failures.

In reliability and systems engineering, the concept is closely related to, but distinct from, terms such as fault and failure. A fault is an underlying defect in a part; a failure is the loss of the intended function in operation. A fejlfunktion is typically the outcome observed when a fault manifests during use.

Causes can include design flaws, manufacturing defects, wear and aging, environmental stress (such as temperature, moisture, or vibration), software bugs, or integration errors between subsystems.

Detection and mitigation involve testing, diagnostics, monitoring, and maintenance. Techniques such as fault isolation, logging, watchdog timers, redundancy, and error handling aim to reduce the impact of fejlfunktion and to keep systems safe and available. Corrective actions include repair, replacement, software patching, or redesign.

The concept is relevant across sectors such as electronics, automotive, aerospace, medical devices, and information technology. In safety-critical contexts, addressing fejlfunktion is essential for reliability metrics, maintenance planning, and risk assessment.