OBD-II trouble code
P0660: Intake Manifold Tuning Valve Control Circuit/Open (Bank 1)
The valve that retunes the intake manifold's length is not responding to its control circuit on Bank 1. The giveaway is not a general loss of power but a flat spot at one specific end of the rev range.
Quick facts
- System
- Powertrain
- Category
- Air Intake / Manifold Control
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $90 – $900
- DIY difficulty
- Intermediate DIY
What does P0660 mean?
An intake manifold is not just a set of pipes. Air arriving at a closing intake valve slams to a stop and sends a pressure wave back up the runner, which reflects off the plenum and returns. Time that returning wave to arrive just as the valve opens again and it packs extra air into the cylinder for free — no turbocharger, no extra fuel, just tuning. The catch is that the timing depends on runner length and on engine speed, so any fixed manifold can only be right at one part of the rev range.
The intake manifold tuning valve is how manufacturers escape that compromise. It opens or closes a passage between plenum chambers, or switches a butterfly in a crossover pipe, and in doing so changes the effective length of the intake tract. Long at low revs for torque, short at high revs for breathing. Done properly it puts a deliberate step in the torque curve — which is why a stuck valve produces such a distinctive complaint.
That complaint is the most useful thing about P0660. The engine does not feel generally weak. It feels normal across most of the rev range and hollow at one end of it, because half the torque curve is still being delivered by a correctly tuned manifold and the other half is not. Which half depends on where the valve is stuck. A valve parked in the long-runner position gives an engine that pulls cleanly away from a stop and then runs out of breath near the top. Parked short, it feels lethargic and lazy off idle and comes alive higher up. Two drivers with the same code will describe opposite problems, and both are correct.
P0660 is the general and open-circuit member of the Bank 1 group, and it is the one to expect when the module cannot detect its control circuit at all. That covers an unplugged or corroded connector, a break in the control wire, a lost feed, and a solenoid whose coil has failed open — the last being common enough on older vehicles to be worth testing for rather than assuming wiring. Where the design uses a vacuum-operated valve driven by an electrical solenoid, remember that this code speaks only for the electrical half. A split diaphragm or a perished vacuum hose leaves the electrical circuit healthy and the valve immobile, so a car with the mechanical complaint and no code is still worth inspecting.
Bank 1 is the side of the engine containing cylinder number one. On an inline engine there is only one bank and this code covers the whole manifold. On a V or flat engine the other side has its own valve and its own code, P0663.
This is worth fixing but it is not urgent. Nothing is being damaged; the engine is simply running on a manifold that is stuck in one of its two configurations, which is exactly how every engine built before variable intake tuning ran for decades. Expect a fuel economy penalty and a soft patch in the power delivery rather than harm.
Common causes
- Unplugged, unlatched or corroded connector at the tuning valve solenoid
- Open circuit in the control wire between the module and the solenoid
- Tuning valve solenoid coil failed open internally
- Blown fuse on the feed side shared with other intake solenoids
- Carbon build-up seizing the tuning valve shaft or butterfly in one position
- Split vacuum actuator diaphragm or perished supply hose on vacuum-operated designs
- Broken linkage or detached actuator rod between the actuator and the valve shaft
- Corroded terminals from water sitting in the valley of a V engine or under the cowl
- Failed control driver inside the engine control module
Symptoms
- Check engine light on
- A hollow spot at one end of the rev range while the rest of the range feels normal
- Reduced low-speed pull away from a stop, or an engine that runs out of breath near the top
- Fuel economy down modestly, most noticeably in the driving that uses the affected part of the range
- Slightly rougher or busier idle on designs where the valve position affects idle airflow
- No symptoms at all on some vehicles, with the code found only during unrelated diagnosis
- Engine noise character changing at the rev point where the valve should have switched
- Hesitation during acceleration through the transition point
Diagnostic steps
- 1.Note where in the rev range the engine feels flat. That single observation tells you which position the valve is stuck in and is free.
- 2.Locate the tuning valve and its solenoid for this specific engine. On some designs it is an electric actuator on the manifold; on others it is a vacuum motor with a remote electrical solenoid, and the two are diagnosed differently.
- 3.Inspect the connector before testing anything. An unlatched or corroded plug is the most common cause of the open-circuit version of this code and costs nothing to find.
- 4.Measure the solenoid coil resistance and compare it against specification. An open coil confirms the valve rather than the wiring and stops the diagnosis there.
- 5.Check for the feed voltage at the solenoid with the ignition on, then check the control side while commanding the valve with a scan tool.
- 6.On vacuum-operated designs, apply vacuum directly to the actuator with a hand pump and watch the linkage move. A diaphragm that will not hold vacuum is the fault and the electrical circuit is innocent.
- 7.With the manifold accessible, move the valve shaft by hand through its full travel. Stiffness or a hard stop short of full travel means carbon rather than electrics.
- 8.Command the valve open and closed with a scan tool while watching manifold pressure or the position feedback, if the design provides it, to confirm whether it physically responds.
- 9.Check the wiring along the route across the top of the engine, where heat cycling and previous service work are the usual sources of an open.
Repair cost
$90 – $900
A connector repair or reseat, which is a genuinely common outcome on this code, is $90 to $200 including diagnosis. The solenoid or actuator itself is typically $40 to $260 in parts, and the labour is what decides the bill: mounted externally on the manifold it is under an hour, buried under a plenum it can be three or more, so the same nominal repair ranges from about $150 to $700 depending purely on where the manufacturer put it. Vacuum hose or diaphragm repair on vacuum-actuated designs is $80 to $250. Carbon cleaning of a seized valve shaft is $150 to $450. A complete intake manifold, needed where the tuning valve is integral and not separately serviceable, is $400 to $900 and is worth confirming before agreeing to it, since many designs do allow the valve alone to be replaced.
Estimate your repair
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Open the Repair Cost Estimator with intake manifold runner control actuator replacement preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.