P2004 - Intake Manifold Runner Control Stuck Open Bank 1
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System
Powertrain (Engine & Gearbox)
OBS!This code is in a manufacturer-specific range. The description may vary depending on the vehicle manufacturer.
Related Fault Codes
Technical Description
P2004 means that the Engine Control Module (ECM) has detected that the Intake Manifold Runner Control (IMRC) flaps for Bank 1 are stuck in the open position. The IMRC system adjusts the airflow path through the intake manifold to improve engine performance and fuel economy. At low RPMs, the flaps close to increase air velocity (swirl/tumble), and at higher RPMs, they open to allow maximum air volume. The ECM monitors flap position via a feedback sensor or by monitoring current draw on the actuator. If the sensor voltage indicates the flaps are open when they should be closed, P2004 is stored. This mismatch disrupts the air-fuel ratio and affects NOx emissions levels.
Possible Causes
Mechanical binding or sticking of the intake manifold runners due to carbon buildup
Faulty IMRC actuator (solenoid, motor, or vacuum diaphragm)
Failed IMRC position sensor or broken linkage/lever arm
Wiring issue (short to voltage in signal circuit) or ECM software fault
Symptoms
Recommended Solution
Workflow
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
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