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P2004 — Intake Manifold Runner Control Stuck Open Bank 1

Manufacturer-specificPowertrain (engine & transmission)

P2004 indicates the Engine Control Module (ECM) has detected that the Intake Manifold Runner Control (IMRC) actuator on Bank 1 is stuck in the open position. The IMRC system adjusts intake runner length to optimize engine torque and power across different RPM ranges. When the mechanism fails to close or respond to commands, the ECM sets this code and may illuminate the Check Engine Light.

Symptoms

What causes it — most likely first

1. Failed IMRC actuator motor

The electric motor or gear mechanism inside the actuator assembly has seized or worn out, preventing the flap/valve from moving from the open position.

2. Broken or disconnected linkage

Physical connecting rods, bushings, or pivots between the actuator and the runner flap are broken, disconnected, or jammed.

3. Vacuum-operated actuator failure

On some engines, a vacuum diaphragm controls the runner position; a torn diaphragm, disconnected hose, or leaking vacuum source leaves the flap stuck open.

4. Wiring or connector issue

Damaged wiring, corroded pins, or a loose connector to the IMRC motor prevents proper operation signals or power delivery.

5. Faulty IMRC position sensor

The feedback sensor that tells the ECM the runner position has failed, causing the ECM to receive incorrect data and set the code.

6. ECM software or hardware fault

Rarely, the ECM itself may have a software calibration issue or internal hardware failure preventing correct command of the actuator. This is the least common cause.

How it's diagnosed

  1. Perform a visual inspection of the intake manifold area for obvious damage, disconnected vacuum lines, or broken linkage components.
  2. Use a scan tool to monitor IMRC position sensor data in real-time while manually commanding the actuator to verify it responds and moves through its range.
  3. Check the IMRC actuator electrical connector for corrosion, damage, or loose fit; test for proper voltage and ground at the connector.
  4. Test the actuator motor windings for opens or shorts using a multimeter; measure resistance against factory specifications.
  5. Inspect all vacuum lines feeding the IMRC system (if applicable) for leaks, cracks, or disconnections.
  6. As a final step, verify the ECM is sending the correct command signal with a oscilloscope or advanced diagnostic tool; rule out other causes before suspecting the ECM.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationManufacturer-specific (P1/B1/C1/U1)
Related codesP2000 — Nox Adsorber Efficiency Below ThresholP2001 — Nox Adsorber Efficiency Below ThresholP2002 — Particulate Filter Efficiency Below ThP2003 — Particulate Filter Efficiency Below ThP2005 — Intake Manifold Runner Control Stuck OP2006 — Intake Manifold Runner Control Stuck C

Frequently asked

Can driving with P2004 cause engine damage?

Typically not, but continued driving will result in poor driveability, reduced fuel economy, and failed emissions tests. The engine is mechanically safe but will run poorly.

Is the IMRC actuator the same as the intake manifold runner control solenoid?

Yes, the terms refer to the same component. It may be called an actuator, solenoid, or control valve depending on the manufacturer, but all describe the device that moves the runner flaps.

I was told to replace the PCM/ECM for this code. Is that necessary?

Almost never. PCM failure is among the rarest causes of P2004. Most shops replace the actuator, repair wiring, or fix vacuum issues long before the computer needs replacement. Verify all physical components and electrical circuits before condemning the ECM.

Will this code clear itself after repairs?

The code may clear after a driving cycle if the underlying fault is fixed and the ECM confirms the system is operating correctly. A scan tool can verify the code is resolved and no longer pending.