P1515 — Intake manifold resonance flap

Causes

• Faulty resonance flap actuator (motor/servo)
• Damaged or seized flap mechanism (carbon buildup or broken linkage)
• Wiring fault: open/shorted connector, corroded pins or damaged harness
• Faulty position sensor or feedback circuit on the actuator
• Failed intake manifold runner control module or engine control module (rare)
• Vacuum leak or loss of actuation pressure where vacuum actuates the flap (if vacuum‑operated)

Symptoms

• MIL/Check Engine lamp illuminated
• Reduced low‑end torque or vague throttle response
• Surging or stumbling at low rpm, especially under load
• Unusual intake noise or whistle from manifold
• Possible limp‑in mode on some vehicles

What to check

• Read stored freeze‑frame and live data with a capable scanner — note RPM, load, and recorded conditions
• Attempt to actuate resonance flap from diagnostic tool and observe movement
• Visually inspect intake manifold, flap, actuator, linkage and vacuum lines (if present) for damage or carbon buildup
• Check connectors for corrosion, bent pins, secure fit and water intrusion
• Measure supply voltage and ground at the actuator connector with key on/engine off
• Check position sensor signal (voltage or potentiometer) while commanding flap through full travel

Signal parameters

• Actuator supply: ~12 V battery voltage at key on (verify within battery voltage ± 1 V)
• Actuator control: PWM duty cycle from ECU — 0–100 % (varies with commanded position)
• Position feedback: ~0.1–4.9 V (potentiometer type) or a discrete feedback indicating end‑stop (manufacturer specific)
• Expected changes: feedback voltage/position should follow commanded changes smoothly; no sudden drops or open circuit
• Resistance: actuator motor/solenoid resistance typically low (ohms to tens of ohms) — compare to spec in workshop manual

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