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WARNING: This page is about a different car, the 2001 Saab 9-3. However, it is still accessible from the selected car via links, so may be relevant.

General condition for this diagnostic trouble code: Atmospheric pressure must exceed 72 kPa as well as coolant and intake air temperature must exceed -7°C.
3 min since engine started. Engine speed 1300 -2200 RPM. Load 250 -500 mg/comb. Closed loop is active and stable. Air mass per combustion stable. Purge active. Coolant temperature above 70 °C. When all the conditions are fulfilled, the number of combustions during 2 sensor transitions is counted.