Wiring fault such as a short to a higher voltage source on the boost control B supply circuit; Corroded, damaged or loose connector terminals at the boost control device or control unit; Faulty boost control B actuator, solenoid or electronic wastegate/vane motor with an internal fault; Fault in the relay, fuse or power supply feeding the boost control circuit; Charging system fault causing system voltage that is too high; Internal fault in the engine control unit driver circuit.

P005F

Turbocharger/Supercharger Boost Control B Supply Voltage Circuit High.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
0: AreaFuel and air metering, auxiliary emission controls
5F: FaultThe specific fault in that area

What it means

P005F is the generic code for a high voltage condition in the supply circuit of Boost Control B, the second turbocharger or supercharger boost control device on the engine. The engine control unit monitors the voltage on this supply circuit and set the code because it read higher than the expected range. Which component is 'B' (for example a second turbo actuator or a bank 2 control device) depends on the model and engine.

Symptoms

Engine warning light on
Loss of power or reduced boost, often with the engine in limp mode
Turbo or boost control actuator not responding correctly
Poor acceleration or hesitation under load
Possible additional boost or actuator-related fault codes stored

Possible causes

Wiring fault such as a short to a higher voltage source on the boost control B supply circuitlikely
Corroded, damaged or loose connector terminals at the boost control device or control unitlikely
Faulty boost control B actuator, solenoid or electronic wastegate/vane motor with an internal faultpossible
Fault in the relay, fuse or power supply feeding the boost control circuitpossible
Charging system fault causing system voltage that is too highpossible
Internal fault in the engine control unit driver circuitrare

How to diagnose

Read all stored codes and freeze frame data, noting battery voltage, engine load and conditions when the code set, then check for related boost, actuator or voltage codes
Check the battery and charging system voltage with the engine running to rule out an overvoltage condition
Inspect the wiring and connectors to the boost control B device for chafing, heat damage, corrosion, water ingress and bent or pushed-back pins
Identify which device is Boost Control B on this model and engine using the manufacturer wiring diagram
Check the relevant fuses and relays and the supply voltage at the device connector with the ignition on, comparing against specification
Test the supply wire for a short to a higher voltage source and check the wiring for continuity back to the control unit
Test the actuator or solenoid resistance and operation against the manufacturer's data, using a suitable diagnostic tester for active tests if supported
Clear the code and road test to see whether it returns, checking live data for boost target against actual boost

How to fix

Repair or replace damaged wiring or a shorted supply circuit
Clean, repair or replace faulty connectors and terminals
Replace the boost control B actuator or solenoid if it fails testing
Replace a faulty relay or fix the supply feed to the circuit
Repair the charging system if the supply voltage is found to be too high
Replace or repair the engine control unit only after all wiring and component faults are ruled out, and follow the manufacturer's procedure

Can I keep driving?

Medium severity

The car can usually be driven carefully for a short time, often in reduced power mode, but get it checked soon. Continued driving with uncontrolled boost risks further faults and possible engine or turbo damage.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.