Since the early years of the trade, car mechanics were often referred to as ‘auto-doctors’, a figuration most readily discernible in the field’s advertisements and trade journals. This linking of car repair craft skills to the clinical expertise of medical physicians is often suggested through depiction of this ‘auto-doctor’ using a stethoscope. Beyond being emblematic of a doctor’s vocation, referencing this tool underlines a tradition common to both professions: namely, of training the expert’s senses to detect and analyse problems in cars and human bodies by their sounds. However with the advent of more visual forms of diagnosis (e.g., x-rays) in the 1950s and 1960s, medical auscultation’s real potential was more and more frequently put into question. Roughly at the same time, similar shifts from sonic to visual means of diagnosis (e.g., oscilloscopes) occurred in the car mechanics trade. This article explores connections between the two very different fields of medical diagnosis and car repair through an investigation of their ‘sonic skills’ (the listening skills and other skills needed to employ the tools for listening). This comparison is developed first through delineating the bodily, cognitive and socio-technical aspects of diagnostic listening, for which examining different teaching strategies for learning such techniques in both fields are revelatory. We examine each technique’s key dispositions and contexts of enactment, including uses of the stethoscope and other tools, particular listening protocols and bodily postures and ways of sharing and communicating about perceived acoustic information within professional settings. Finally, we explore how listening is equally engaged in the construction of professional identities, including relationships between experts and non-experts.