Catalytic converter
Applies to Audi A3s with petrol engine: The Audi A3 must only be used with unleaded petrol; otherwise the catalytic converter will be irreparably damaged.
Never allow the fuel tank to run completely dry, as the irregular supply of fuel can cause misfiring. This allows unburnt fuel to enter the exhaust system, which can cause overheating and damage to the catalytic converter.
Diesel particulate filter
Applies to Audi A3s with diesel engine: The diesel particulate filter can filter out almost all soot particles contained in the exhaust gas. In normal driving conditions the filter is self-cleaning. In addition, the diesel particulate filter is also automatically regenerated at certain intervals. In this case, the indicator lamp 
does not come on. An increased idling speed and a certain odour may be noticed while this is happening.
does not come on. An increased idling speed and a certain odour may be noticed while this is happening.Should the self-cleaning or automatic regeneration function of the filter not be able to operate, e.g. when the Audi A3 is continuously used only for short trips, the filter becomes obstructed with soot and the indicator lamp for the diesel particulate filter lights up ►Link.
for the diesel particulate filter lights up ►Link.WARNING!
The exhaust system is very hot when the Audi A3 is being driven and after the engine has been switched off.
- Never touch the tailpipes when they are hot – risk of burns!
- Because of the high temperatures which can occur in the emission control system (catalytic converter or diesel particulate filter), do not park the Audi A3 where the exhaust can come into contact with flammable materials under the car (e.g. on grass or at the forest edge) – risk of fire!
- Do not apply any underseal agents in the area around the exhaust system - risk of fire!