OBD-II Diagnostic Trouble Code
P0660 — Intake Manifold Tuning Valve Control Circuit/Open
P0660 means the ECM detected an open or fault in the intake manifold tuning valve control circuit, the actuator that changes intake runner length or plenum volume to improve torque. The command circuit was open or didn't match the expected state. It's mostly found on gas medium-duty engines; some diesel manufacturers use the code for related intake-valve actuators.
Severity 3/5
Truck-relevant
Service this week
Severity
Service this week
Intake Manifold Tuning Valve Control Circuit/Open
Code
P0660
Category
Powertrain
Subsystem
Air Flow
Truck-relevant
Yes
What this means for truckers
P0660 (Intake Manifold Tuning Valve Control) — on engines with variable intake runner length, the tuning valve actuator has a circuit fault.
Before you replace parts — try this first
P0660 on the Air Flow system is most often unplugged, corroded or broken connector at the tuning valve actuator — not a dead part. On commercial diesels especially, work these in order before spending money on parts:
- Confirm the symptoms. Match what your truck is doing to the Symptoms section below. If the code is set but the symptoms are not there, clear the code and re-test after a drive cycle — it may not return.
- Clean and dry the sensor connector. Water, road salt, or oil seeping into a connector is the #1 fake sensor failure. Disconnect, look for green corrosion or moisture, spray with electrical contact cleaner, dry, reseat. Many faults clear here for $0.
- Inspect the wiring harness. Trace the wire from the sensor toward the ECM — look for chafing against the engine block, melted insulation near the turbo or exhaust, or pinch points where a clamp has rubbed through.
- Test the sensor before swapping it. Most Common Causes (below) list the expected voltage or resistance range — a $20 multimeter saves a $300 sensor swap that does not fix the problem.
- Only then, replace the part. Use the OEM or a tier-1 aftermarket. Cheap sensors throw the same code in two weeks.
Symptoms
Usually a mild loss of low-end torque or a flat spot at a certain rpm, slightly worse fuel economy, and the check-engine light. The engine starts and runs normally otherwise.
Common causes
- CommonUnplugged, corroded or broken connector at the tuning valve actuator ($50–$250)
- CommonFailed tuning valve solenoid or actuator (open coil) ($150–$500)
- OccasionalOpen or shorted control wire ($100–$350)
- RareFailed ECM driver ($1200–$3500)
How to fix
Inspect the actuator connector and harness for damage, especially near the intake
When to use: First step
Measure the actuator coil resistance and compare to spec
When to use: To check the actuator
Command the valve with a scan tool and verify the control signal reaches the actuator
When to use: When the actuator tests good
Replace the actuator or repair the wiring
When to use: Based on test results
Affects most
No specific vehicle pattern found in our complaint database. This code can appear on any vehicle that supports OBD-II diagnostics.
Related
- → Browse all DTC trouble codes
- → Decode a VIN to check codes for your truck
- → Owner-operator maintenance guides
- → P0670 — Glow Plug Control Module Circuit
- → P0671 — Cylinder 1 Glow Plug Circuit
- → P0672 — Cylinder 2 Glow Plug Circuit
- → P0673 — Cylinder 3 Glow Plug Circuit
- → P0674 — Cylinder 4 Glow Plug Circuit
Frequently Asked Questions
Can I drive with code P0660?
P0660 is severity 3 — plan service within a few days. Performance is likely degraded already (you may feel reduced power, harsher shifts, or slightly worse fuel economy). Continuing to drive risks additional damage to adjacent components.
How much does it cost to fix P0660 on a commercial truck?
Total repair cost ranges $50–$3500 depending on the root cause. The cheapest fix is usually the first one listed below — Unplugged, corroded or broken connector at the tuning valve actuator — which is also the most common. On commercial trucks the cost is usually higher than passenger vehicles due to part availability and shop labor rates ($120–185/hour at most truck shops, vs $90–130 at general auto shops). DIY-capable fixes (sensors, hoses, filters) are at the low end; major component replacements (turbo actuator, high-pressure fuel pump, transmission solenoid pack) are at the high end. Always diagnose with a scan tool BEFORE replacing parts — guessing wrong on a $1,500 turbo actuator when the actual issue was a $30 boost hose is a common expensive mistake.
Will P0660 fail a DOT inspection?
P0660 is generally not a direct DOT inspection fail item by itself. Inspectors focus on safety-critical systems (brakes, steering, tires, lights, hours-of-service). However, the check engine light alone can trigger additional inspection scrutiny. Best practice: fix the code and clear it before a planned inspection.
What's the difference between P0660 and related codes?
P0660 is closely related to: P0670 (Glow Plug Control Module Circuit), P0671 (Cylinder 1 Glow Plug Circuit), P0672 (Cylinder 2 Glow Plug Circuit), P0673 (Cylinder 3 Glow Plug Circuit). These codes share the same subsystem (air-flow) and often appear together. If you see this code, scan for the full code list — fixing the root cause usually clears multiple companion codes at once. If only P0660 is set without the companions, the issue is more isolated.
How do I prevent P0660 from coming back after a repair?
For P0660 (Intake Manifold Tuning Valve Control Circuit/Open), prevention centers on the air flow system. Service air filter on time. Clean MAF sensor at every air filter change. Inspect intake boots/hoses for cracks — vibration kills them eventually.