Visual Inspection
WARNING: This page is about a different car, the 2003 Volkswagen EuroVan, 2002 Volkswagen EuroVan, 2001 Volkswagen EuroVan, 2000 Volkswagen EuroVan, and 1999 Volkswagen EuroVan. However, it is still accessible from the selected car via links, so may be relevant.
Prior to retrieving DTCs, perform a thorough visual inspection of underhood components. Check ground connections located on intake manifold, ground cable between engine and vehicle body and that battery cables are clean and tight. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
Check vacuum hoses for breakage and blockage. Check electrical wiring and harness connectors for damage and corrosion. Repair as necessary.