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P0660Intake Manifold Tuning Valve Control Circuit/Open (Bank 1)

The control circuit for the Bank 1 intake manifold tuning valve is open or not responding electrically.

Definition

The intake manifold tuning (IMT) valve changes the effective intake runner length or opens a communication passage to boost torque across the RPM range, and the PCM drives its solenoid or motor while monitoring the circuit. P0660 sets when the PCM detects an open circuit or missing feedback on the Bank 1 valve control circuit. Symptoms are usually subtle — reduced low-end torque or soft top-end power depending on the valve's default position — along with an illuminated MIL that will fail an emissions inspection. The engine otherwise runs normally.

Common causes

  • Failed intake manifold tuning valve solenoid or actuator motor (open winding)
  • Disconnected, corroded, or backed-out terminal at the valve connector
  • Open wiring between the PCM and the valve, often chafed near the manifold
  • Valve linkage seized by carbon so the actuator was previously overloaded and failed
  • Failed PCM driver circuit (least common)

Common misdiagnoses

  • Entire intake manifold replaced when only the solenoid/actuator or connector is faulty
  • Throttle body cleaned or replaced for a perceived power loss
  • MAP or MAF sensor replaced even though this is an actuator circuit code
  • PCM replaced before testing the valve winding and harness

Troubleshooting steps

  1. 1.Locate and inspect the tuning valve

    Find the IMT valve/actuator on the Bank 1 manifold and check that its connector is seated, its terminals are clean, and the linkage moves freely by hand where accessible.

  2. 2.Command the valve with a scan tool

    Use bidirectional control to actuate the tuning valve and listen or watch for movement; no response supports an open circuit or dead actuator.

  3. 3.Measure the actuator winding

    Disconnect the valve and measure solenoid resistance (typically in the 20-80 ohm range for solenoids — check the service spec); an open (OL) reading condemns the valve.

  4. 4.Test the control circuit

    Verify continuity from the PCM connector to the valve connector (under 1 ohm) and confirm power or ground supply to the valve per the wiring diagram.

  5. 5.Clear codes and confirm operation

    After repair, run the engine through low and high RPM ranges or re-command the valve, then verify the code does not reset over a complete drive cycle.

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