Damaged, chafed or broken wiring between the control unit and the boost control solenoid or actuator; Corroded, loose or pushed-out pins in the solenoid or actuator connector; Failed boost control solenoid or actuator with an open internal coil or motor circuit; Blown fuse or fault in the power supply or earth to the boost control device; Heat damage to wiring or connector close to the turbocharger or exhaust; Internal driver fault in the engine control unit.

P0045

Turbocharger/Supercharger Boost Control A Circuit/Open.

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
45: FaultThe specific fault in that area

What it means

P0045 means the engine control unit has detected an open circuit in the control circuit for turbocharger or supercharger boost control solenoid or actuator 'A'. The control unit drives this device to regulate boost pressure, and it set the code because the electrical feedback from the circuit did not match what it commanded, typically indicating a break or very high resistance. The exact device (wastegate solenoid, variable geometry vane actuator or similar) depends on the engine.

Symptoms

Engine warning light on
Reduced power or car going into limp mode
Boost pressure too low or not building
Turbo overboost or erratic boost in some cases
Poor acceleration or hesitation under load
Possible increase in fuel consumption

Possible causes

Damaged, chafed or broken wiring between the control unit and the boost control solenoid or actuatorlikely
Corroded, loose or pushed-out pins in the solenoid or actuator connectorlikely
Failed boost control solenoid or actuator with an open internal coil or motor circuitlikely
Blown fuse or fault in the power supply or earth to the boost control devicepossible
Heat damage to wiring or connector close to the turbocharger or exhaustpossible
Internal driver fault in the engine control unitrare

How to diagnose

Read all stored codes and freeze frame data, noting engine load, rpm and temperature when the fault set, and check for related boost or actuator codes
Visually inspect the wiring and connector at the boost control device for heat damage, chafing, corrosion or loose pins
Check the relevant fuses and relays, as shown in the wiring diagram for that model and engine
Use a scan tool with bi-directional controls to command the solenoid or actuator and see whether it responds, where the model supports this
Measure the device's coil or motor resistance and compare it with the manufacturer's specification
Check for supply voltage, earth and a control signal at the connector with the ignition on
Test wiring continuity between the connector and the control unit, and check for shorts to earth or supply, with the battery disconnected
Check the vacuum lines and mechanical movement of the wastegate or vane linkage, as the procedure varies by engine

How to fix

Repair or replace damaged wiring, using proper soldered or crimped and sealed joints
Clean, repair or replace the corroded or damaged connector terminals
Replace the faulty boost control solenoid or actuator, then carry out any adaptation or calibration the manufacturer requires
Replace the blown fuse after finding and correcting the cause of the failure
Re-route or shield wiring that is exposed to excessive heat
Repair or replace the engine control unit only after all wiring and component faults have been ruled out

Can I keep driving?

Medium severity

The car can usually be driven carefully for a short time, often in limp mode with reduced power. Get it fixed soon, and avoid heavy loads, since uncontrolled boost can risk engine or turbo damage.

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