P2004
Intake Manifold Runner Control Stuck Open Bank 1P2004 is a generic OBD-II powertrain diagnostic trouble code: Intake Manifold Runner Control Stuck Open Bank 1. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P2004 means
P2004 is stored when the PCM detects that the intake manifold runner control (IMRC) actuator on engine bank 1 — the bank containing cylinder number one — is stuck in the open position and cannot be commanded closed. The IMRC system uses movable flaps or butterfly valves inside the intake manifold runners to change the effective runner length and cross-section. At low RPM the flaps close, lengthening the effective runner and improving charge velocity for better low-end torque and idle quality. At higher RPM they open, reducing restriction for maximum airflow and top-end power.
When the flap sticks open, the low-RPM benefits are lost: idle quality deteriorates, throttle response at low speeds feels sluggish, and fuel consumption can increase because the engine works less efficiently in part-throttle city driving. At highway speeds the open-runner state is actually normal, so the fault may be less perceptible during high-speed cruising. The PCM detects the fault either via a dedicated runner position sensor that reports flap angle, or by monitoring manifold absolute pressure (MAP) response — a properly closing flap should produce a measurable pressure change that a stuck flap will not.
The most common mechanical cause is a broken plastic actuator lever arm connecting the solenoid motor to the runner flap shaft. Engine heat makes this lever brittle over time, and it eventually snaps, leaving the flap in the default open position. Carbon build-up on direct-injection engines can also seize the flap shaft in place. Electrical faults in the solenoid control circuit or the position sensor are less common but should be ruled out before disassembling the manifold.
P2004 is a bank-specific code — if the opposite bank is also affected, P2005 will be stored simultaneously. Repair urgency is moderate: drivability is reduced but the engine is not at immediate risk, though extended operation with poor fuel distribution can cause uneven cylinder wear over time.
Common causes
Most-frequently reported root causes when P2004 is logged.
-
1
Broken plastic actuator lever arm connecting solenoid to runner flap shaft
-
2
Carbon deposit build-up seizing the runner flap shaft (common on direct-injection engines)
-
3
Faulty IMRC actuator solenoid unable to generate sufficient force
-
4
Disconnected or cracked vacuum line to the vacuum-controlled actuator
-
5
Debris or foreign object obstructing the flap from closing
-
6
Defective intake manifold runner position sensor
-
7
Damaged or corroded wiring or connector at the IMRC solenoid
-
8
Faulty MAP sensor giving incorrect feedback used to verify flap movement
-
9
Failed PCM output driver for the IMRC solenoid circuit
Symptoms drivers notice
How to diagnose P2004
A typical diagnostic flow when this code is present.
-
1
Retrieve all DTCs and freeze-frame data; check for companion codes (P2005, MAP sensor codes, IMRC solenoid codes)
-
2
Visually inspect the IMRC actuator linkage on bank 1 — look for a broken plastic lever arm connecting the solenoid to the flap shaft
-
3
With the engine off, manually attempt to move the runner flap shaft; check for carbon seizure or mechanical binding
-
4
Inspect vacuum lines to the actuator (if vacuum-operated) for cracks, disconnections, or blockage
-
5
Check the IMRC solenoid connector for corrosion and test solenoid coil resistance against manufacturer specification
-
6
Using a scan tool or bi-directional controller, command the IMRC actuator and observe the position sensor feedback or MAP response
-
7
Inspect the intake manifold runners for carbon accumulation around the flap shaft — cleaning or manifold replacement may be required on high-mileage direct-injection engines
-
8
Confirm repair by clearing the code and performing a drive cycle that exercises the IMRC system through the operating RPM range
Related powertrain codes
- P2000 — NOx Adsorber Efficiency Below Threshold Bank 1
- P2001 — NOx Adsorber Efficiency Below Threshold Bank 2
- P2002 — Diesel Particulate Filter Efficiency Below Threshold Bank 1
- P2003 — Diesel Particulate Filter Efficiency Below Threshold Bank 2
- P2005 — Intake Manifold Runner Control Stuck Open Bank 2
- P2006 — Intake Manifold Runner Control Stuck Closed Bank 1
Frequently asked questions
Is P2004 serious enough to stop driving immediately?
No immediate safety concern exists. The vehicle remains drivable, though low-RPM performance and fuel economy are degraded.
Why is the broken plastic lever such a common cause?
OEM actuator lever arms are often moulded from nylon or glass-filled plastic to keep weight and cost low. Prolonged exposure to intake manifold heat cycles makes the material brittle, and the lever eventually snaps.
Can P2004 appear alongside P2005?
Yes, on V6 or V8 engines both banks can fail simultaneously, especially when the root cause is age-related brittleness of the actuator arms.
Will cleaning the intake manifold fix P2004 on a GDI engine?
If carbon build-up is seizing the flap shaft, a walnut-blast or chemical intake cleaning can free the flap and resolve the code.
Does a stuck-open IMRC flap cause any long-term engine damage?
Not directly or immediately. The engine will run, but sustained poor idle quality and uneven charge distribution can contribute to spark plug fouling over time.
Disabling P2004 in software
RaceTune can permanently disable P2004 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
ECUs with a P2004 disable in our catalogue
Confirmed coverage from our recipe database — we support many more families. Upload your file and our identifier will match it automatically.
- Bosch MD1CS001 verified 1 software version
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
Got P2004 in your scan?
Upload your ECU file — we'll identify the exact software version and confirm whether a disable is available for your car.
Upload your file