P2004
Intake Manifold Runner Control Stuck Open (Bank 1)
The intake manifold runner control (IMRC) flap on bank 1 is stuck in the open position. The IMRC swirls or tumbles intake charge at low rpm by closing one runner per cylinder; when stuck open, low-end torque drops and the engine may misfire on cold starts.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
What we see in the workshop
ON FORD ECOBOOST
Intake manifold runner control stuck open is commonly carbon fouling on the runner flaps. Cleaning is usually sufficient before replacing the manifold.
Common causes
Ordered by how often each turns out to be the cause.
- Carbon buildup blocks flap travelCommon
- IMRC actuator or vacuum motor failedPossible
- Linkage rod broken or disconnectedPossible
Parts involved
- Intake Manifold Runner
- IMRC Actuator
- Intake Manifold
P2004 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.