I have 2002 Audi A4 Quatrro V6 3.0 Litre Engine Tiptronic. Odometer with 100,000 miles
I can drive for 3 hours and the gauge stays cool all the time. On other days, the gauge may stay High all the time.
I took it for emission test the other day and failed. Diagnostic test indicated that the catalytic converters -both right and left catalytic converters have low efficiency. I plan to change the timing belt, oxygen sensors(4), spark plugs and wires and thermostat before I change the catalytic converters. Is there anything else that I should change to prevent future damage to the cat converters?