Vehicles using AAT engine list:

Engine AAT, a 2.5 TDi from early 90s Audi 100, commonly faces EGR valve clogging, causing rough idling and reduced performance. Diagnose by checking for soot buildup and testing EGR function; cleaning or replacing the valve often resolves issues. Injector wear can cause poor fuel atomization; test injectors for spray pattern and replace if faulty. Turbocharger seals may leak, leading to smoke and power loss; inspect and rebuild or replace turbo if needed. Regular oil changes with quality diesel oil prevent premature wear. Use fuel additives to keep injectors clean. Monitoring boost pressure helps detect early turbo or intake leaks.