2008 Audi S5 Repair and Maintenance

A guide to problems, costs, maintenance and repair for your 2008 Audi S5

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2008 Audi S5 Problems

Decreased Power and Fuel Economy from Carbon Buildup

The 2008-2017 Audi S5 uses the 3.0TFSI and 4.2FSI direct injection engines. These engines are subject to carbon buildup in the intake system which can cause power loss, OBD codes and a check engine light, and a rough idle. In normal engines, the engine is cleaned by the gasoline flowing through the injectors and into the intake system, however, the S5 uses direct injection so gasoline does not flow through common carbon buildup areas. 

Possible trouble codes include: P0300P0301P0302P0303P0304, P0305, P0306.

The solution is to remove the intake manifold and professionally clean the intake manifold, intake ports on the cylinder head, and the intake valves. This may need to be done in as few as 20,000 miles.

No Start after Refueling and Popping Noise from Trunk

Popping sounds from the rear of the vehicle may be heard moments after starting the engine, or when slowing to a stop. This noise is from the leak detection pump filling the fuel tank with air, and releasing to retest the system when it finds a fault. The sequence of faults identifying this issue are as follows:

  • Succession of loud pops from rear of vehicle
  • Pops go away, and fuel economy decreases 
  • Check engine light illuminates
  • OBD trouble code P2404 and/or P0441 is stored
  • Engine will not start after refueling (must crank for over 30 seconds)
  • Vibration when slowing to a stop

The cause is a valve which is mounted on the front of the intake manifold, commonly called the N80 valve, or EVAP system purge valve. The valve is designed to open under specific circumstances, but a worn valve will remain open at all times, preventing the pressurization of the fuel tank. 

Correction of the issue is to replace the N80 valve with the latest revision. 

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