P2004 means Intake Manifold Runner Control Stuck Open (Bank 1). The intake manifold runner control on bank 1 is not moving as commanded and appears stuck open. The runners change the intake path length to improve torque and power across the rev range. It is a generic OBD-II code, so the definition is the same on any make, but the most likely cause varies by engine; confirm with a scan tool and the service information for your vehicle before buying parts.
What P2004 means
Most vehicles built in the last two decades use electronic throttle control instead of a throttle cable: the accelerator pedal carries two or three position sensors, and the throttle body has a motor and two position sensors of its own. The computer compares the redundant sensors constantly, and any disagreement triggers reduced-power mode as a safety measure. Older engines with a throttle cable control idle with a separate idle air control valve.
P2004 symptoms
- Check engine light
- Loss of low-speed torque or top-end power
- Rough idle on some engines
Common causes of P2004
- Sticking runner valves from carbon buildup
- Failed runner actuator or solenoid
- Vacuum leak to a vacuum-operated actuator
- Broken linkage
- Wiring or connector fault
How to diagnose P2004
- Inspect the actuator and linkage for movement
- Check vacuum supply on vacuum-operated systems
- Command the runners with a scan tool and watch the position sensor
- Check for carbon buildup in the manifold
Can you drive with P2004?
Usually yes, with some loss of performance; repair it to restore power.
P2004 tips
Carbon buildup can stick the runners on direct-injection engines; cleaning may free them, but a seized actuator needs replacing.
Will P2004 clear itself?
If the fault stops, the computer turns off the check engine light by itself after several drive cycles without seeing it again, and the code stays in memory as history for a while. Clearing P2004 with a scan tool after a repair is fine, but if the cause is still there the code returns, sometimes within one drive. Disconnecting the battery also clears codes on most vehicles, but it erases learned fuel trims and idle settings as well.
Related codes
| Code | Meaning |
|---|---|
| P0171 | System Too Lean (Bank 1) |
| P0101 | Mass or Volume Air Flow Circuit Range/Performance |
Guides that help
When it is more than a sensor
Throttle and idle codes are fixed at the throttle body, the pedal, a sensor or a leak. If those check out and the engine still runs poorly, a compression test separates a control problem from a worn engine; compare engines by code on our engines page.
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