Scan Tool Recommendation
To properly diagnose vehicle, vehicle manufacturer recommends use of Scan Tool (VAG 1551/VAG 1552, VAS 5051/VAS 5052) and Test Box (VAG 1598). Generic scan tools may not be capable of performing all diagnostic functions e.g. Readiness Code, Idle Check and Automatic Test Sequence etc. Ensure ignition switch is in OFF position when performing resistance tests. Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure.
NOTE:
Before replacing any component that scan tool suggests are faulty. Ensure that all wiring connections and harness connectors are okay. Ensure that power and ground circuits are functioning properly. For circuit identification, see ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.