Internal control is essential to ensure the reliability of accounting information, especially in high-value and high-frequency business environments such as automotive dealerships. This study investigates the internal control weaknesses in the sales and cash receipt procedures at PT Astra International Tbk – Auto2000 Yasmin Branch, based on fieldwork conducted through a seven-month internship. Key issues identified include delayed issuance of receipts (BTU), overlapping functions between sales and cashier roles, manual transaction recording, and lack of managerial oversight over down payment (DP) flows. These conditions create vulnerabilities that align with the Fraud Diamond Theory, particularly the elements of opportunity and capability, while also signaling deficiencies in several components of the COSO Internal Control Framework. The study uses a qualitative case study approach, collecting data through direct observation, interviews, and document analysis, supported by triangulation, member checking, and peer debriefing for validation. Findings lead to five proposed improvements: the implementation of a real-time e-receipt system, clear segregation of duties, integration of sales and accounting systems, daily cash reconciliation by supervisors, and internal training on SOPs and ethics. These recommendations aim to enhance fraud prevention, accountability, and information reliability within the automotive transaction cycle.