This focused study guide is designed for professional technicians and advanced automotive students preparing for the ASE L4 (Advanced Engine Performance Specialist) Certification Exam . It provides 190 scenario-based multiple-choice questions , each with detailed explanations to strengthen diagnostic skills and reinforce service knowledge. 📘 Topics and Question Distribution: Computerized Powertrain Controls Diagnosis - 36 Questions Emission Control Systems Diagnosis - 38 Questions Engine-Related Service and Repair - 45 Questions Fuel and Air Induction System Diagnosis - 30 Questions General Powertrain Diagnosis - 4 Questions Ignition System Diagnosis - 37 Questions This resource delivers targeted practice to help candidates review essential concepts, refine test-taking strategies, and prepare with confidence for the ASE L4 exam. This study guide was built using student study notes that were reformatted into questions with the assistance of AI. AI was also used to verify the accuracy and ensure alignment with the exam topics. It’s meant to help learners practice and strengthen understanding but should not be treated as an official or primary reference. Sayit Publication cannot be held liable for any unintentional errors. This book is a concise overview and does not include comprehensive coverage of all exam topics. It is intended to help candidates refine their knowledge before the exam. This resource serves as a supportive study tool to reinforce understanding and build confidence. For a well-rounded preparation, learners are encouraged to combine it with official publications and authoritative study sources. Sayit Publication does not guarantee specific exam results and assumes no liability for outcomes. Use of this material is at the user's discretion and responsibility.