Online courses often include interface designs that do not support a positive learner experience. Literature shows a variety of heuristics to detect issues of online courses. While heuristic-based inspection of usability is a dominant method for evaluating digital systems, these methods cannot be easily transferred to online courses. To close this gap, we identified an initial set of social, technical, and pedagogical related items (STP) heuristics based on literature. Next, we analyzed this set using empirical data from two online courses. In total, we analyzed 195 problems with the goal to substantiate a final set of 14 STP heuristics. This new set allows for efficiently evaluating online courses by supporting evaluators and instructional designers in uncovering the most crucial issues and improving the learner experience. Finally, based on this work, we discuss a definition of learner experience for the emerging field of learner experience design and research.