P2004: Intake Manifold Runner Control Stuck Open (Bank 1) (Meaning, Causes, Fixes)

What P2004 means

Many engines have flaps or butterfly valves inside the intake manifold, called an intake manifold runner control (IMRC) system, that the powertrain control module (PCM) opens and closes to change how air flows into each cylinder. The flaps are usually mounted on a shaft that runs through all the intake ports on one cylinder head, so one stuck or binding flap can stop them all. They are moved by an electric actuator or, on some models, a vacuum diaphragm fed by a PCM-controlled solenoid (OBD-Codes.com, RepairPal). P2004 is stored when the PCM detects that the Bank 1 runner control is stuck in the open position. Bank 1 is the side of the engine with cylinder 1; inline engines have only Bank 1. OBD-Codes.com describes it as a generic OBD-II code for 1996 and newer vehicles (it names Mazda, Ford, Dodge, Jeep and Kia), with repair steps that vary by make and model. It explains that the PCM watches the runner position sensor and other inputs such as the MAP, manifold air temperature, throttle position and MAF sensors, and sets the code when it doesn't see the expected change after commanding the flaps to move; the light may only come on after the fault is seen on several drives. Note on sources: the two sources describe the system's purpose differently. OBD-Codes.com says the flaps create a swirl that improves fuel atomization and are partly closed at start-up and idle, then opened as the throttle opens, while RepairPal says the system varies runner length and lets more air flow at higher RPM, with the PCM deciding based mainly on throttle position and crankshaft position inputs. Designs vary by maker, so check your vehicle's service information. P2005 is the matching stuck-open code on Bank 2, and P2006 and P2007 are the stuck-closed codes (RepairPal).

Severity: can I keep driving?

Drive with caution, fix soon

Get it diagnosed within a reasonable time. RepairPal rates P2004 Moderate, meaning it may not threaten safety or drivability right away but should still be checked. OBD-Codes.com gives no severity rating. Expect weaker performance, especially at low engine speeds, and lower fuel economy until it is fixed. If the engine surges badly, stalls, or other warning lights come on, have it checked sooner.

Common symptoms

• Check engine light on (RepairPal, OBD-Codes.com)
• Reduced or poor engine performance, especially at low RPM (OBD-Codes.com, RepairPal)
• Reduced fuel economy (OBD-Codes.com, RepairPal)
• Engine surge (OBD-Codes.com)

Likely causes

Roughly most to least common, based on the sources below. Your vehicle may differ.

1. Failed or defective IMRC actuator or actuator solenoid (OBD-Codes.com, RepairPal)
2. Loose or binding intake manifold runner flaps or linkage, including flap screws or rivets that loosen or fall out and carbon build-up inside the manifold (OBD-Codes.com, RepairPal)
3. Open or shorted wiring in the IMRC control circuit, or a corroded actuator connector (OBD-Codes.com, RepairPal)
4. Bad intake manifold runner position sensor (OBD-Codes.com)
5. Faulty MAP sensor (OBD-Codes.com)
6. Leaking or disconnected vacuum hoses on vacuum-operated systems (RepairPal suggests checking them)

Diagnostic steps you can do

1. Read all stored codes and freeze frame data and write them down, then clear the code and see if it returns; RepairPal notes P2004 can sometimes set in error (OBD-Codes.com, RepairPal).
2. Check for technical service bulletins (TSBs) for your vehicle, since the problem may be a known issue with a known fix (OBD-Codes.com, RepairPal).
3. Inspect the IMRC actuator wiring and connector for broken wires, loose connections and corrosion; OBD-Codes.com says these connectors are prone to corrosion (OBD-Codes.com, RepairPal).
4. On vacuum-operated systems, check the vacuum hoses to the actuator for cracks or disconnection (RepairPal).
5. With the actuator disconnected from the shaft, check whether the runner flaps move freely or bind (OBD-Codes.com).

Typical fixes

• Clean or repair a corroded IMRC actuator connector
• Repair open or shorted wiring in the IMRC circuit
• Replace leaking or disconnected vacuum hoses on vacuum-operated systems
• Replace a failed IMRC actuator, actuator solenoid or runner position sensor if testing confirms it
• Repair or replace binding runner flaps, linkage or the intake manifold; RepairPal says the manifold may need to be removed to inspect the valves

Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.

Related codes

• P2015 Intake Manifold Runner Position Sensor/Switch Circuit Range/Performance (Bank 1)
• P0101 Mass Air Flow (MAF) Circuit Range/Performance
• P0106 MAP/Barometric Pressure Circuit Range/Performance
• P0122 Throttle/Pedal Position Sensor/Switch A Circuit Low

Also listed in this guide:

All Intake manifold runner codes (P2004–P2019) →

FAQs

Sources

1. OBD-Codes.com: P2004 Intake Manifold Runner Control Stuck Open Bank 1 (Stephen Darby, ASE)
2. RepairPal: P2004 Intake Manifold Runner Control Stuck Open (rated Moderate)