A4 Quattro Cabriolet L4-2.0L Turbo (BWT) (2009)
Crankcase Pressure Regulator Valve: Customer Interest
Engine - MIL ON/Rough Idle/ DTC's P0507/P2279/P2187
01 MIL on, engine stalls or idles erratically immediately after cold start in extremely cold weather (below 20°F)
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December 1, 2009
Affected Vehicles
Condition
Weather is extremely cold (below 20°F or -6.7°C), and one of the following conditions is present:
^ MIL on. Possible DTCs (P0507, P2279, or P2187).
^ Uneven idle or engine immediately stalls prior to shifting out of Park at first cold start. Engine operation normal after warm-up.
Technical Background
It is normal for condensed water to accumulate in the engine oil during extended periods of cold weather (below freezing) and excessive vehicle
short-trip operation. This water usually evaporates when the engine reaches operating temperature and exits through the crankcase ventilation system.
However, if the vehicle is mainly used for short trips and the engine does not reach operating temperature, an excessive amount of condensed water may
collect in the crankcase pressure regulating valve and freeze over night (Figure 1). This could lead to a temporary malfunction of the crankcase pressure