Fuel and air

P0047 — Turbo/Supercharger Boost Control 'A' Circuit Low

Severity: medium Drive with care, to a shop

What P0047 means

The engine computer regulates boost pressure through a control device, usually a boost control solenoid that operates the wastegate or variable-geometry vanes. P0047 sets when the voltage in that control circuit is lower than expected, for example from a short to ground, an open circuit or a failing driver inside the PCM. Boost can no longer be regulated properly, and the engine often goes into limp mode.

Symptoms

  • Check Engine light on
  • Reduced power and sluggish acceleration
  • Weak or delayed boost
  • Worse fuel economy
  • Limp mode

Possible causes

  1. Failed boost control solenoid
  2. Damaged wiring or poor connection in the control circuit
  3. Wire shorted to ground
  4. Faulty PCM output driver
  5. Vacuum leaks or control pressure problems
  6. Faulty boost pressure sensor or actuator position sensor

How to diagnose

  1. Read all codes and freeze-frame data and note any other boost-related codes
  2. Inspect the wiring harness and boost solenoid connector for chafing, corrosion or heat damage
  3. Check charge-air hoses, intercooler connections and vacuum lines for cracks and leaks
  4. Measure the solenoid resistance and compare with the manufacturer's spec
  5. Test the control circuit with a multimeter for a short to ground or an open circuit
  6. Command the solenoid with a scan tool active test and confirm it responds
  7. Check that the wastegate or variable-geometry mechanism moves freely
  8. Compare commanded and actual boost pressure in live data

Common fixes

  • Replace the boost control solenoid
  • Repair the wiring or replace the connector
  • Replace cracked vacuum hoses or charge-air pipes
  • Reflash or replace the PCM if its driver is faulty

Questions and answers

What does P0047 mean?

The PCM detected low voltage in boost control circuit 'A'. The usual culprits are the solenoid, wiring or connector, and less often the PCM itself.

Can I drive with a P0047 code?

Only briefly and carefully, such as to a shop. Power will be reduced, and uncontrolled boost can put the turbo and engine at risk.

How do I fix P0047?

Start by checking the wiring, connector and boost solenoid, then the vacuum lines and wastegate movement. After the repair, clear the code and verify boost on a road test.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.