This bulletin applies to 2013-2016 Audi A6, S6, A7, S7, A8 and S8 vehicles equipped with a 4.0L engine. A metallic whistling or grinding noise may be heard from the engine area when at idle speed. The sound usually only occurs when the engine is warm, and the MIL may be sporadically on. DTCs may be stored in the ECM including P227900 (intake air system leak) and/or P050700 (idle control system rpm higher than expected).
A leak in the crankcase breather module (pressure regulating valve) can cause this condition. A fabric-reinforced internal membrane of the crankcase breather module has been developed. Open the filler cap to check whether the sound is affected when the cap is open. If so, replace the oil separator breather module.
Parts required are as follows:
- 079103542E..........oil separator
- 079129717J...........left intercooler gasket
- 079129717K..........right intercooler gasket
- N90442501............retaining clips (two)
- N90489801............retaining clips (two)
