Damaged, chafed or corroded wiring in the boost control supply circuit (short to earth or high resistance); Corroded, loose or water-contaminated connector at the boost control actuator or solenoid; Blown fuse or faulty relay supplying the boost control circuit; Faulty boost control actuator or solenoid drawing excessive current and pulling the supply down; Weak battery or charging system fault causing low system voltage; Poor earth connection affecting the circuit; Fault inside the engine control unit supply driver.

P005E

Turbocharger/Supercharger Boost Control B Supply Voltage Circuit Low.

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
5E: FaultThe specific fault in that area

What it means

P005E is the generic SAE J2012 code for a low voltage fault in the supply circuit feeding the turbocharger or supercharger boost control 'B' system. The engine control unit monitors the supply voltage to the boost control actuator or solenoid and has seen it below the expected range. Which component 'B' refers to, and which pin or fuse supplies it, depends on the make, model and engine, so check the wiring diagram for the specific vehicle.

Symptoms

Engine warning light on
Reduced power or limp mode
Poor or inconsistent boost, or no boost
Turbo lag or sluggish acceleration
Possible whistling or hissing if the boost control is not holding position
Other boost or actuator codes stored alongside it

Possible causes

Damaged, chafed or corroded wiring in the boost control supply circuit (short to earth or high resistance)likely
Corroded, loose or water-contaminated connector at the boost control actuator or solenoidlikely
Blown fuse or faulty relay supplying the boost control circuitpossible
Faulty boost control actuator or solenoid drawing excessive current and pulling the supply downpossible
Weak battery or charging system fault causing low system voltagepossible
Poor earth connection affecting the circuitpossible
Fault inside the engine control unit supply driverrare

How to diagnose

Read all stored codes and freeze frame data, noting battery voltage, engine load and whether other codes such as charging or boost faults are present
Check battery condition and charging voltage to rule out a general low voltage problem
Visually inspect the wiring and connectors to the boost control actuator or solenoid for chafing, heat damage, corrosion and water ingress
Check the relevant fuse and relay against the vehicle wiring diagram, including their terminals
Measure the supply voltage at the actuator connector with the ignition on and while the actuator is commanded, comparing with specification
Check the circuit for short to earth and for resistance on the supply and earth wires with the control unit disconnected, following the manufacturer procedure
Check the actuator or solenoid resistance and current draw against the specification for that engine
Clear the code and road test, then recheck for return of the fault under boost

How to fix

Repair or replace damaged wiring and terminals in the supply circuit
Clean, dry or replace corroded connectors and secure them properly
Replace the blown fuse only after finding and fixing the cause of the overload, or replace a faulty relay
Replace the boost control actuator or solenoid if it is shorted or drawing excess current
Repair the battery or charging system fault, or clean and tighten earth connections
Check for a manufacturer software update only if one is documented for this fault, and replace the control unit only once all else is ruled out

Can I keep driving?

Medium severity

The car can usually be driven carefully for a short time, but expect reduced power and possible limp mode. Get it checked soon, as running without proper boost control can affect drivability and, on some engines, risk further faults.

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