This study investigates the retained effect of prior elevated-temperature exposure on the coefficient of static friction of self-mated polymer–polymer sliding pairs. This is one of the first studies analysing how short-term thermal history affects the static friction of self-mated engineering polymers after cooling to room temperature. Three engineering thermoplastics, PA6, PET, and POM, were tested under technically dry contact conditions. Before friction measurements, the specimens were heated at 50–100°C for 30 min and then stabilized at room temperature for 30 min. Static friction was measured using an inclined pin-on-plate test setup under nominal contact pressures of 0.67, 1.16, and 1.65 MPa. The results were supported by SEM observations, areal surface roughness measurements, Vickers microhardness analysis, and statistical evaluation. Prior thermal exposure caused a strongly material-dependent and non-linear response. PA6–PA6 showed an increase in static friction from approximately 0.23–0.24 at room temperature to 0.32–0.45 after heating, with the highest values after exposure to 50–60°C. In contrast, PET–PET and POM–POM generally showed lower static friction after thermal exposure. The results indicate that even short-term prior heating may produce retained surface-layer changes affecting motion initiation after cooling. Therefore, thermal history, polymer type, contact pressure, surface topography, and near-surface mechanical response should be considered when designing polymer sliding pairs operating under start-up and stop conditions.