Diagnosing with Fuel Trim | O2 Data, Pulse Width, and Real Scan Tool Tips
Learn how to diagnose engine performance issues using short and long term fuel trim data. This hands-on scan tool demo shows live readings from a 2009 Subaru Outback and explains how the ECU responds to rich and lean conditions.
Full Description
In this video, we connect a scan tool to a 2009 Subaru Outback and walk through how to use generic OBD-II data instead of vehicle-specific parameters to diagnose engine performance. Learn how to:
🔹 Customize PID lists to show only the data you want
🔹 Read and understand short-term and long-term fuel trim
🔹 Monitor oxygen sensor data in real time
🔹 Identify rich and lean conditions using live engine response
🔹 Understand pulse width modulation and injector control
🔹 Diagnose drivability problems using fuel trim patterns
We also demonstrate how the system compensates for induced fuel mixture issues and discuss what normal vs abnormal data looks like. Whether you’re a DIY enthusiast or a pro tech, this video is packed with practical info.
📌 Have a question about your fuel trims? Drop it in the comments!