"N51, N52K and N52T: Idle Fluctuation During Engine Warm-up Phase. After a cold engine start, the idle speed may be unstable or start fluctuating up and down slightly while the vehicle is stopped. On vehicles with automatic transmissions, roughness or shuddering may be felt during this warm-up period when diving away slowly in ""D"" or in ""R"" without depressing the accelerator pedal. No relevant errors are stored in the DME fault code memory, and these symptoms are no longer present once the engine is at operating temperature (> 90C). Unfavorable DME software"