Purpose: Many organizations expect their service engineers, or frontline employees (FLEs), to behave as brand advocates by engaging in favorable communication about the brand and its offerings toward customers. However, this approach is not without risk as customers may be disappointed or even frustrated with brand advocacy behavior in many service encounters. The purpose of this paper is to study the impact of FLEs’ brand advocacy on customer satisfaction with the service encounter, and identify the conditions under which the effects are detrimental. This paper specifically considers service issue severity and product newness as contingency conditions. Design/methodology/approach: Building on social identification theory, the paper builds a conceptual model, which is empirically tested using a data set that matches data from service engineers, customers, and archival records from the after-sales service department of a globally operating business-to-business print and document management solutions provider. Findings: This paper finds that brand advocacy behavior harms customer satisfaction especially in service encounters that involve simple service issues (e.g. maintenance) for products that are new to the market. Fortunately, brand identification can compensate this negative effect under many service conditions. While the joint effect of brand identification and advocacy is most beneficial for severe service issues of new products, no effect on customer satisfaction was found for established products. Practical implications: This paper identifies those service situations in which brand advocacy is advisable and guides managers toward achieving more favorable customer evaluations. Originality/value: Past research has considered several FLE branding activities in the frontline but the effects of brand advocacy have not been isolated. In addition, most studies have assumed the effects of employee brand-related behaviors on customer satisfaction to be universally positive rather than negative and focused on antecedents and not on moderators and consequences.