Turbocharger/Supercharger Boost Control 'A' Circuit Low
Your turbocharger's boost pressure control system is reading too low, like a blood pressure cuff showing dangerously low readings when the patient is actually fine. The ECU can't get the boost control valve to respond properly, leaving your engine unable to build full turbo pressure.
The ECM monitors the boost control solenoid circuit voltage and the resulting manifold absolute pressure (MAP). It expects a specific voltage signal and corresponding boost pressure rise when commanding the solenoid open. A low circuit voltage or inability to build boost triggers this fault.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Boost Control Solenoid Voltage | 11-14V when commanded | Below 8V or open circuit |
| Manifold Absolute Pressure | Expected boost rise per command | No pressure increase or insufficient rise |
Code P0047 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, P0047 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.