P1520

What the Code Means

Code P1520 points to a fault in the exhaust-side camshaft position actuator. The VANOS system adjusts valve timing by changing the camshaft position relative to the crankshaft to optimize power, fuel economy, and emissions. The fault sets when the DME detects that the actual exhaust camshaft position doesn't match the target. Likely causes include a sticking VANOS solenoid, wiring problems (open circuit, short), or a faulty DME itself.

Symptoms

• Engine: power loss at low rpm, rough idle
• Fuel economy: increased consumption
• Warning lights: Check Engine light on

Diagnosis and Repair

Step 1: Read the Codes

Connect ISTA or INPA and read the fault codes. Confirm that code P1520 is active.

Step 2: Test the VANOS Solenoid

Measure the resistance of the exhaust-side VANOS solenoid with a multimeter. Spec: 7–12 ohms. If resistance is out of range, the solenoid is bad.

Step 3: Replace the Solenoid

If faulty, replace the solenoid with the original BMW OEM part (11367579070).

Step 4: Reset Adaptations

After replacement, reset the DME adaptations with a diagnostic tool.

Related Problems

Ignoring code P1520 can lead to serious consequences:

• Timing chain jump: a faulty VANOS solenoid disrupts synchronization, which can cause the chain to jump and the valves to contact the pistons, requiring an engine rebuild.
• Catalytic converter damage: unburned fuel entering the exhaust system can destroy the catalytic converter.

Fix the fault at the first signs to avoid expensive repairs.