Failed camshaft position actuator solenoid (also known as the VANOS solenoid); Dirty or clogged oil passages in the actuator or solenoid screen; Wiring damage or corroded connector at the camshaft actuator; Low engine oil level or degraded oil quality; Sticking or mechanically failed camshaft phaser assembly; Faulty camshaft position sensor (though less common); Engine control module (DME) software issue or internal fault

DTC codes / BMW codes / P1520

P1520 · BMWB Camshaft Position Actuator Bank 1

Q: What does code P1520 mean?

B Camshaft Position Actuator Bank 1. P1520 on BMW vehicles indicates that the engine control module (DME) has detected a fault in the variable camshaft timing system for Bank 1, specifically the 'B' camshaft position actuator. The computer monitors the actuator's electrical circuit and the camshaft's actual position relative to the commanded position, and it sets this code when the measured camshaft timing deviates from the target or when the actuator circuit shows an electrical fault.

P1520 on BMW vehicles indicates that the engine control module (DME) has detected a fault in the variable camshaft timing system for Bank 1, specifically the 'B' camshaft position actuator. The computer monitors the actuator's electrical circuit and the camshaft's actual position relative to the commanded position, and it sets this code when the measured camshaft timing deviates from the target or when the actuator circuit shows an electrical fault.

SystemPowertrain

Code typeBMW specific

SeverityMedium

Fix difficultyIntermediate

AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Rough idle or unstable engine speed, especially when cold
Reduced engine power and sluggish acceleration
Poor fuel economy or increased fuel consumption
Occasional engine misfire or hesitation during acceleration
In some cases, the engine may enter limp mode

Common causes, most likely first

Failed camshaft position actuator solenoid (also known as the VANOS solenoid)
Dirty or clogged oil passages in the actuator or solenoid screen
Wiring damage or corroded connector at the camshaft actuator
Low engine oil level or degraded oil quality
Sticking or mechanically failed camshaft phaser assembly
Faulty camshaft position sensor (though less common)
Engine control module (DME) software issue or internal fault

How to diagnose and fix it

Check engine oil level and condition; top off or change oil if necessary
Inspect the camshaft actuator solenoid connector and wiring for damage or corrosion
Remove and clean the camshaft actuator solenoid, checking for debris on the screen
Swap the bank 1 camshaft actuator solenoid with a known-good unit to see if the code follows
Use a scan tool to command the camshaft actuator and observe actual camshaft position response
Perform a resistance and voltage drop test on the actuator solenoid circuit
If the actuator and wiring are good, inspect the camshaft phaser for mechanical wear or sticking

Before replacing the VANOS solenoid

A dirty oil screen on the VANOS solenoid is a frequent cause that is often overlooked; cleaning it can resolve the code without parts replacement.
The code can be set by low oil pressure or sludged oil passages even when the solenoid itself tests good, so oil maintenance history is critical.
Swapping the bank 1 and bank 2 solenoids is a quick diagnostic step on V8 and inline-six engines to see if the fault moves.
After repairs, the DME may require a relearn or adaptation reset to clear the code and restore proper camshaft timing.
In some cases, a failing camshaft position sensor can mimic a VANOS actuator fault, so always verify sensor signals before condemning the actuator.

Can I keep driving with P1520?

You can usually drive the vehicle with this code, but avoid aggressive acceleration and high engine loads until it is repaired. Prolonged driving with a faulty camshaft actuator can lead to poor fuel economy, increased emissions, and potential damage to the catalytic converter.

Tools that help

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Guidance is general and written for BMW vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.