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P codepowertrainMedium severity

P0664Intake Manifold Tuning Valve Control Circuit Low (Bank 2)

The control circuit for the Bank 2 intake manifold tuning valve is reading a lower voltage than expected, usually from a short to ground or an open circuit.

Definition

The PCM operates the intake manifold tuning (runner control) valve on Bank 2 to change effective runner length or plenum volume for better torque across the RPM range, and it monitors feedback voltage on the valve's control circuit. P0664 sets when that circuit voltage stays below the expected threshold while the PCM is commanding the valve, indicating a short to ground, an open circuit, or a failed actuator winding. Symptoms are usually subtle: reduced low-end torque or top-end power, slightly worse fuel economy, and an illuminated MIL; the engine typically still runs normally otherwise. The vehicle may fail an emissions inspection with the MIL on.

Common causes

  • Wiring harness damage on the Bank 2 tuning valve circuit (chafed insulation shorted to ground or a broken wire)
  • Corroded, bent, or backed-out terminals at the tuning valve connector
  • Failed intake manifold tuning valve actuator (open or shorted solenoid/motor winding)
  • Binding or carbon-seized tuning valve flap loading the actuator until the driver circuit faults
  • Blown fuse or bad supply feed to the actuator
  • Faulty PCM driver circuit (rare)

Common misdiagnoses

  • Replacing the entire intake manifold when only the actuator or wiring is at fault
  • Replacing the tuning valve actuator when the harness has a short to ground
  • Replacing the MAP sensor because manifold airflow codes are assumed
  • Cleaning or replacing the throttle body, which is unrelated to the runner control circuit

Troubleshooting steps

  1. 1.Scan and record freeze frame data

    Note whether the Bank 1 counterpart (P0661) is also present, which would point to a shared supply or ground rather than the Bank 2 actuator itself.

  2. 2.Command the tuning valve with a bidirectional scan tool

    Actuate the Bank 2 valve while listening/watching for movement; no response confirms a circuit or actuator fault rather than an intermittent.

  3. 3.Inspect the connector and harness at the Bank 2 actuator

    Look for chafing where the harness crosses the manifold, green corrosion on terminals, and verify terminal tension with a test pin.

  4. 4.Measure actuator winding resistance

    Compare to specification (typically a few ohms to ~30 ohms depending on design); near 0 ohms indicates a shorted winding and an open (OL) reading indicates a failed actuator.

  5. 5.Check the control wire for a short to ground

    With the connector disconnected and key off, an ohmmeter from the PCM-side control wire to chassis ground should read open; continuity means a harness short.

  6. 6.Verify valve movement and PCM output

    Confirm the flap moves freely by hand where accessible, then back-probe the control circuit for the commanded voltage/duty cycle before condemning the PCM.

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