Intake Manifold Tuning Valve Control Circuit (Bank 1)
The P0660 code indicates that the Powertrain Control Module (PCM) has detected an electrical malfunction in the control circuit of the intake manifold tuning valve for Bank 1. This code is set when the PCM observes voltage or resistance levels in the circuit that fall outside of the expected manufacturer specifications.
While this code rarely causes a vehicle to stall or break down, it can lead to reduced engine torque, poor fuel economy, and increased emissions. It should be diagnosed and repaired soon to restore optimal engine performance.
Common symptoms
- Illuminated Check Engine Light
- Reduced engine power or torque, especially at higher RPMs
- Hesitation or stumbling during acceleration
- Slight decrease in fuel economy
- Rough or erratic engine idle
Likely causes
- Faulty intake manifold tuning valve (IMTV)
- Corroded, damaged, or loose wiring and connectors in the IMTV circuit
- Carbon buildup causing the tuning valve to bind mechanically (triggering circuit faults via high current draw)
- Broken vacuum lines (if the valve is vacuum-actuated but electrically controlled)
- Faulty Powertrain Control Module (PCM) (rare)
What to check before replacing parts
Visually inspect the wiring harness and connector for the intake manifold tuning valve.
Look for: Look for frayed wires, melted insulation, corrosion on the pins, or a loose connection that could cause an open or short circuit.
Measure the internal resistance of the intake manifold tuning valve using a digital multimeter.
Look for: Compare the resistance reading to the manufacturer's specifications; an infinite reading indicates an open internal coil, while a very low reading indicates a short.
Check for proper power and ground at the tuning valve connector with the ignition on.
Look for: Verify that the control circuit is receiving the correct reference voltage and ground from the PCM; lack of voltage indicates a wiring or PCM issue.
Perform a bi-directional test using an advanced scan tool to command the tuning valve on and off.
Look for: Listen for a click or observe the valve linkage moving; if the scan tool commands it but it doesn't move, the valve or its circuit is faulty.
Remove the tuning valve and inspect the intake manifold runners for carbon buildup or mechanical binding.
Look for: Check if the valve flap moves freely by hand; heavy carbon deposits or a stuck flap mean the manifold or valve needs cleaning or replacement.
This page explains the generic P0660 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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