P1520 on BMW: How to Diagnose & Fix
Intake Manifold Runner Control Circuit Fault
1 BMW model · 1 documented issue · 1 critical · $900-$3,000 repair
P1520 on BMW by model: symptoms, diagnosis and fix
The E39 M5's S62 V8 commonly develops VANOS-related problems as mileage and age increase, especially from worn piston seals, leaking solenoid pack seals, and failing solenoids. Owners report cold-start rattle, reduced low-end torque, intermittent limp behavior, and check engine lights tied to cam timing deviations. This is a well-known E39 M5 issue discussed extensively in owner communities and supported by BMW service information covering VANOS fault diagnosis.
Common Symptoms
- cold start rattle
- check engine light
- loss of low-end torque
- rough idle
- hesitation under acceleration
- intermittent limp mode
How to Fix
Diagnosis typically includes scanning for camshaft timing and VANOS activation faults, checking oil condition/pressure, and listening for startup rattle from the front of the engine. Repair usually involves rebuilding the VANOS units with upgraded seals, replacing failed solenoids or solenoid seals, and correcting any oil leaks or timing-related wear. Many owners address both banks preventively while the front of engine is apart.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Beisan BS064 S62 upgraded solenoid O-ringsCross-refBS064, 11367830828, 11367830829
Solenoid seal repair component. Fitment: US-market 2000-2003 E39 M5 S62; one BS064 set covers both solenoid banks.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (3)
- BMW M5 (E39) PH Buying Guide - Powertrainbuying-guide
- Beisan VANOS Seals Repair Kit - E39 M5 S62parts-reference
- Beisan VANOS Rattle Repair Kit - E39 M5 S62parts-reference
P1520 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P1520 mean on a BMW?
P1520 stands for "Intake Manifold Runner Control Circuit Fault." This manufacturer-specific code (common on Ford) indicates a circuit fault in the Intake Manifold Runner Control (IMRC) system, which uses motorized or vacuum-actuated flaps in the intake to vary airflow length for better low- and high-RPM performance. The computer detected that the IMRC actuator circuit is open, shorted, or not responding as commanded. You may notice reduced power, hesitation, or poor throttle response, though some drivers feel nothing. It is generally an electrical or actuator/linkage issue rather than internal engine damage. On BMW it is documented across 1 model: M5.
What are the most common causes of P1520?
The most common causes of P1520 are: Faulty IMRC actuator or motor, Open or shorted IMRC wiring harness, Poor or corroded electrical connection at the actuator, Stuck, broken, or seized runner flaps/linkage, Carbon buildup binding the runner plates, Faulty ECM/PCM driver (less common). The specific cause varies by vehicle.
How much does it cost to fix P1520 on a BMW?
Published repair estimates on BMW range from $900 to $3,000 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.