OBD-II Diagnostic Trouble Code
P1518 — Intake Manifold Runner Control Stuck Open
P1518 is a manufacturer-specific code that commonly means the intake manifold runner control (IMRC) is stuck open and is not moving to the commanded position. The ECM detected this through the runner position feedback. Meaning can vary by OEM.
Severity 3/5
Truck-relevant
Service this week
Severity
Service this week
Intake Manifold Runner Control Stuck Open
Code
P1518
Category
Powertrain
Subsystem
Air Flow
Truck-relevant
Yes
What this means for truckers
P1518 (Intake Manifold Runner Control Stuck Open) — alternate code for IMRC stuck open. Same as P2004.
Before you replace parts — try this first
P1518 on the Air Flow system is most often carbon or debris jamming the runner plates — 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
Weak low-speed torque, sluggish acceleration from a stop, rough idle, and a check-engine light. High-speed power is usually normal.
Common causes
- CommonCarbon or debris jamming the runner plates ($200–$700)
- CommonFailed IMRC actuator ($200–$700)
- OccasionalVacuum leak or broken linkage (vacuum-operated systems) ($80–$300)
- OccasionalWiring or connector fault ($80–$300)
- RareFaulty position sensor ($100–$350)
How to fix
Command the IMRC with a scan tool and watch movement
When to use: First step
Inspect linkage and vacuum lines
When to use: When the actuator does not move
Clean runner plates or replace the intake manifold
When to use: When plates are seized
Replace the IMRC actuator
When to use: When the actuator fails
Affects most
No specific vehicle pattern found in our complaint database. This code can appear on any vehicle that supports OBD-II diagnostics.
Related
Frequently Asked Questions
Can I drive with code P1518?
P1518 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 P1518 on a commercial truck?
Total repair cost ranges $80–$700 depending on the root cause. The cheapest fix is usually the first one listed below — Carbon or debris jamming the runner plates — 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 P1518 fail a DOT inspection?
P1518 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 P1518 and related codes?
P1518 is closely related to: P1517 (Inferred Engine Coolant Temperature Performance), P1519 (Intake Manifold Runner Control Stuck Closed), P1565 (Cruise Control Servo Stuck). 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 P1518 is set without the companions, the issue is more isolated.
How do I prevent P1518 from coming back after a repair?
For P1518 (Intake Manifold Runner Control Stuck 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.