1. Retrieve Fault Codes: Connect an OBD2 scanner to the vehicle’s OBD port. Upon powering on the scanner, it’ll communicate with the vehicle’s Electronic Control Unit (ECU) and retrieve any stored fault codes.

2. Interpret Fault Codes: The scanner displays one or more fault codes, each with a specific meaning. These codes typically consist of a letter (usually “P” for Powertrain faults) and four digits. For instance, P0100 indicates a malfunction in the Mass Air Flow (MAF) sensor circuit.

3. Consult Fault Code Manual or Database: To accurately understand the fault code’s meaning, technicians refer to relevant fault code manuals or online databases. These resources provide detailed code explanations, including potential causes, effects, and recommended repair procedures.

4. Analyze Possible Causes: Based on the fault code’s meaning and manual recommendations, technicians begin analyzing possible causes. This may involve checking the operational status of related sensors, wires, connectors, or the ECU.

5. Verify Fault: After identifying possible causes, technicians perform further tests or inspections to validate these assumptions. This may include using a multimeter to measure voltage and resistance, checking wire connections, or observing sensor behavior.

6. Perform Repairs: Once the specific cause is determined, technicians proceed with the necessary repairs. This may involve replacing faulty sensors or components, repairing broken or damaged wires, or adjusting ECU parameters.

7. Clear Fault Codes: Upon completing repairs, technicians use the scanner to clear the fault codes stored in the ECU. This ensures the vehicle’s Check Engine Light (CEL) turns off and the system operates normally.

8. Considerations: While fault codes provide valuable information about vehicle malfunctions, they may not always pinpoint a single root cause. In some cases, more in-depth diagnosis and testing are required to determine the issue’s origin. Therefore, technicians need the necessary experience and knowledge to effectively utilize OBD2 fault codes for troubleshooting.