Intake Manifold Runner Control (Bank 1) Stuck Open
The intake manifold runner control valve on bank 1 is stuck in the open position, preventing proper airflow regulation. Think of it like a door that won't close—air flows through when it shouldn't, disrupting engine performance.
The ECU monitors the intake manifold runner control (IMRC) valve position via feedback sensors or solenoid current draw. It expects the valve to transition between open and closed states based on engine load and RPM to optimize airflow dynamics. A stuck-open condition produces an out-of-range electrical signal or absence of expected position change.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| IMRC Valve Position Feedback | Transitions between open (high voltage) and closed (low voltage) based on engine state | Remains fixed at high voltage (open) position; no transition detected |
| IMRC Solenoid Current | 0.5–2.0 amps with state changes corresponding to load | Exceeds or remains below expected range; static current draw indicating mechanical jam |
Code P1550 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P1550 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.