Fuel and air

P005F — Boost Control B Supply Voltage Circuit High

Severity: medium Drive with care, to a shop

What P005F means

The engine control module monitors voltage in the B supply circuit of the boost control device, such as a boost solenoid or electric turbo actuator. When the voltage reads higher than expected, it sets P005F. Common causes are wiring or connector faults, a failed actuator, or rarely an internal driver fault in the module. The ECM may then be unable to regulate boost accurately.

Symptoms

  • Check Engine light on
  • Reduced or erratic power
  • Sluggish throttle response
  • Limp mode activated
  • Poor acceleration under load
  • Occasional unusual turbo noise

Possible causes

  1. Failed boost control solenoid or electric actuator
  2. Wiring short to voltage, open circuit, or high resistance
  3. Corroded or loose connectors
  4. Faulty turbo actuator position sensor
  5. Sticking variable geometry mechanism
  6. Internal ECM driver fault (rare)

How to diagnose

  1. Scan all codes and freeze frame data, clear them, and see whether P005F returns
  2. Inspect the wiring and connector at the solenoid or actuator for damage, corrosion, and chafing
  3. Measure supply voltage and ground at the connector with the ignition on, following the factory wiring diagram
  4. Check the solenoid or actuator coil resistance against specification
  5. Test the wires for opens and shorts to voltage, and check circuit resistance
  6. Compare commanded and actual boost in live data
  7. Check actuator or geometry mechanism movement over its full range
  8. Inspect charge-air hoses and vacuum lines for leaks or cracks

Common fixes

  • Replace the faulty boost control solenoid or actuator
  • Repair or replace damaged wiring and connectors
  • Clean and secure corroded terminals
  • Repair, replace, or reflash the ECM if an internal fault is confirmed
  • Free a sticking turbo mechanism or replace the turbocharger

Questions and answers

What does code P005F mean?

The ECM detected too high a voltage in the boost control B supply circuit. Wiring, a connector, or the boost solenoid is the most common culprit.

Can I drive with P005F?

For a short distance, usually yes, but power is likely limited. Get it diagnosed soon to avoid turbo damage or losing power at a bad moment.

Will clearing P005F fix it?

Clearing the code only helps temporarily. If the cause remains, it will return, so check the wiring, connectors, and solenoid first.

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.