P2004: Intake Manifold Runner Control Stuck Open (Bank 1)

P2004 means the intake manifold runner flaps are stuck in the open position. These flaps change the length of the intake path to optimise airflow at different RPM ranges. When stuck open, the engine loses low-speed torque and may run roughly at idle because airflow is optimised for high RPM only.

P2004 is a fuel system-related diagnostic trouble code classified as moderate severity. When your vehicle's ECU detects this condition, it stores P2004 and illuminates the check engine light.

If your vehicle has triggered P2004, you may notice one or more of these symptoms:

• Check engine light illuminated
• Loss of low-end torque and sluggish acceleration
• Rough or unstable idle
• Slight increase in fuel consumption
• Rattling or fluttering noise from the intake manifold
• Hesitation when accelerating from low RPM

Here are the most common causes of P2004, ranked by how likely they are to be the culprit:

Generally yes, for short-term driving. Generally safe to drive short-term. You may notice reduced low-end torque and slightly higher fuel consumption. Have it repaired within a few weeks to avoid secondary issues.

Follow these steps to pinpoint the root cause of P2004:

1. Listen for a rattling or clicking noise from the intake manifold at idle and during acceleration. Broken flaps or linkage rods often produce a distinct metallic rattle.
2. Remove the intake manifold top cover or use a borescope to visually inspect the runner flaps. Check that all flaps move freely and none are cracked, broken, or jammed with carbon deposits.
3. Test the runner control actuator motor by commanding it on and off with a diagnostic scanner in actuator test mode. You should hear the motor activate and see the flaps move.
4. Check the actuator motor electrically: verify power supply, ground, and motor resistance. A seized motor will draw excessive current or show very low resistance.
5. If the flaps and actuator test good, check for vacuum leaks (on vacuum-actuated systems) or wiring faults between the ECU and the actuator motor.

Repair costs for P2004 vary depending on the root cause and your vehicle. Here are typical estimates:

P2004 behaves differently depending on your vehicle. Select your car below for model-specific causes, known issues, and adjusted cost estimates:

These codes are often seen alongside P2004 or indicate related issues: