Audi S8 D5 — Problems & Common Faults

Elaborate biturbo V8 with cylinder deactivation and a 48-volt belt starter generator for recuperation and launch assistance. The V8 TFSI family is generally well built but has known weak points: the Alusil-coated cylinder bores are costly to restore if damaged, the camshafts are factory-matched to their specific cylinder head and must not be swapped, and the high-pressure pump, injection system and timing chain are frequently cited as failure sources by specialist workshops. Turbochargers run under heavy thermal and mechanical load. A recall affecting this unit is documented for the control module connector in the engine bay: a missing sealing pin can let in moisture and, in the worst case, cause a control module fault leading to engine failure — check for proof the recall was carried out before buying. Oil weeping from the engine and transmission as well as worn control arm bushings occur occasionally on this range according to trade press reports. Stick to oil change intervals and use only approved oil.

• !! Oil Strainer Clogging Leads to Turbocharger Damage from 120,000 km

  The oil strainer inside the engine clogs and cuts off the turbocharger lubricating oil supply. Vehicles fail without warning. In the US, 58 official complaints were registered.

  Symptoms: Sudden engine shutdown without warning, power reduction, turbo noises
  3,000–15,000 $
  Ad Ölsieb 4.0 TFSIoil filter V8 BiTurboturbocharger 4.0 TFSI
• !! Charge Air Hoses Leaking from 80,000 km

  The high boost pressures of the BiTurbo configuration heavily stress charge air hoses and seals. Leaks cause power loss up to limp mode.

  Symptoms: Power dip, engine stumbling under load, noticeable limp mode, whistling noises from the engine bay
  200–800 $
  Ad Ladeluftschlauch 4.0 TFSIintercooler gasket V8 BiTurbo
• !! High-Pressure Pump Wear from 130,000 km

  Hitachi high-pressure pumps wear on the tappet rods. Improved tappet rods were introduced as a replacement part. A pump failure manifests as starting problems and rough running.

  Symptoms: Difficult starting, rough engine running, power loss especially at higher rpm
  800–1,800 $
  Ad high-pressure fuel pump 4.0 TFSIhigh-pressure fuel pump V8 BiTurbo

+ 6 more engine weaknesses + vehicle weaknesses