2A82

BMW describes the complaint precisely in SI B11 02 08: the Service Engine Soon lamp comes on and power drops noticeably after a drive with the engine fully warm, and the car usually runs normally again once the ignition has been cycled. The engine computer sets the code when the camshaft is "late" — it did not reach its target position in the time allowed.

The cause the bulletin names is oil supply. The VANOS control pistons need full oil pressure to move the camshaft in time, and a mechanical restriction or electrical failure of a solenoid, or of its circuit, starves them. Its procedure runs in this order: complete the ISTA test plans; check that the oil-filter cap insert was not lost at the last oil change, because without it unfiltered oil reaches the solenoids; then replace both VANOS solenoids and change the oil.

The hardware end of the list is wear on the camshaft bearing ledge, which the test plan inspects. The bulletin covers N51, N52, N52K and N54 cars built up to January 2010 — the E90 family, E60/E61, E82/E88, E83, E85/E86, E70, E71 and the F01/F02 7 Series.

The VANOS units, the camshafts or a cylinder head get quoted on sight of this code. BMW's own order is the test plan, the filter-cap insert, both solenoids and fresh oil — a worn bearing ledge is something the test plan finds, not a starting assumption.