The BMW E90 engine utilizes two VANOS (variable camshaft timing) solenoids. One for the intake camshaft and one for the exhaust camshaft, mounted to the front of cylinder head. They are responsible for direct oil flow to the VANOS actuator and can become restricted over time on high mileage engines. You can clean or replace the solenoids quite easily if needed. My suggestion is if you have determined you need a VANOS solenoid by cleaning or swapping side to side, replace both solenoids. They are fairly economical and you’re always better off replacing a degrading part. The sealing O-ring for the VANOS solenoid can also leak. If you have an oil leak down the front of cylinder head, inspect solenoid area for fresh oil.

     Inspecting VANOS solenoids once removed: Check VANOS solenoid for cleanliness and or debris. Clean both solenoids and reinstall. If the fault code for camshaft position sensor goes away or swaps position from intake to exhaust (or vice versa), the fault code is being caused by the VANOS solenoid. Replace the solenoid that the code followed. Here are fault codes you may have if a VANOS solenoid is causing your problem, 2A9A Cam sensor, inlet signal invalid for synchronization, 2A98 (P0016) Crankshaft intake correlation value outside ref range, 2A82 intake VANOS jammed mechanically, 2A9B exhaust camshaft sensor signal invalid for synchronization, 2A99 (P0017) Crankshaft position sensor and exhaust camshaft, correlation value outside reference range, 2A87 exhaust VANOS jammed mechanically.

The VANOS solenoids are located at the front of the cylinder head. The intake VANOS solenoid is mounted on the top front of the cylinder head (yellow arrow) and the exhaust VANOS solenoid is mounted on the bottom front of the cylinder head (green arrow).

Working at intake VANOS solenoid, disconnect electrical connector by pressing wire release tab and pulling off.

Remove VANOS solenoid 10mm fastener. (green arrow) Do not reuse this fastener. Throw it away once removed and replace with a new one.

Using a flathead screwdriver, gently lever against metal bracket on VANOS solenoid to extract from cylinder head. Be very careful not to damage solenoid or cylinder head when doing this.

Pull VANOS solenoid sensor out of cylinder head. Have a rag nearby in case some oil drips out of cylinder head when sensor is removed.

The VANOS solenoid O-ring usually stays in the cylinder head when solenoid is removed. Be sure to pull it out before reinstalling solenoid.

Clean VANOS solenoid and be sure it is free of debris. The best way to clean it is to lightly blow it out with compressed air.

Install VANOS solenoid in reverse order of removing. Replace the fastener and O-ring every time sensor is removed from cylinder head. Slide O-ring (green arrow) onto solenoid until it is against spacer (yellow arrow). Lubricate O-ring with clean engine oil to facilitate installation.

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