Overview
What VANOS does
Adjusts the camshaft position relative to the crankshaft. This changes the valve timing: at low RPM, the intake cam is retarded for cleaner exhaust and better idle; at high RPM, the intake cam is advanced for more valve overlap and more power. The exhaust cam is adjusted the other way to reduce pumping loss.
Solenoid clogging is the headline failure
Each VANOS solenoid has a small screen that filters the oil flow. Over time, the screen clogs with varnish, oil-breakdown products, and metal particles. The solenoid can no longer control oil flow precisely; the DME throws a VANOS code.
How to clean VANOS solenoids
Remove the solenoids (a 30–60 minute job on most engines), clean the screens with carb cleaner, test the solenoids with a 12V source, refit. The routine ID for a VANOS adaptation reset targets the DME.
The 2A82 and 2A99 codes
2A82 is VANOS intake control fault (intake solenoid stuck, often intake solenoid screen clogged). 2A99 is VANOS exhaust: control fault, camshaft stuck (more serious; check the exhaust solenoid and the cam phaser).
Stretched timing chain vs VANOS
On N20 and N54 engines, a stretched timing chain can produce VANOS-like symptoms. A VANOS code on a high-mileage N20 or N54 doesn’t automatically mean the solenoid is the problem; check the chain stretch first.
FAQ
What is VANOS?
Variable Nockenwellensteuerung. BMW’s variable valve-timing system.
What does the VANOS solenoid do?
Controls oil flow to a hydraulic actuator that adjusts the camshaft position. Intake and exhaust camshafts each have their own solenoid.
What’s the most common VANOS failure?
Clogged solenoid screens. The solenoids control oil flow; the screens filter the oil; over time the screens clog with varnish. Cleaning the screens is the standard fix.