Iv got a 2010 320d e91 tourer with an engine management light on,initial code from obd reader was P0101 mass air flow. Changed the mass air flow sensor, engine management light came back on after 400 miles. Got the code read by a Snap on solus as 4862 air system, air to egr mass flow plausibility. had an engine carbon clean and the faults back...anyone know what it can be or had similar problems?