What causes fault code P0045?

• Most likely: Faulty turbocharger boost control solenoid/actuator (internal open coil) • Likely: Damaged wiring harness or corroded connectors affecting the circuit • Possible: Blown fuse for the engine management system (shared power supply) • Rare: Faulty Engine Control Unit (ECU) failing to trigger the output driver

How do you fix fault code P0045?

STEP 1: Inspect the connector at the turbo actuator for oxidation or loose pins. Clean with contact cleaner. STEP 2: Perform a resistance test on the solenoid/actuator. Unplug the connector and measure between the pins on the component. Typical values are 10–30 Ohms. 'OL' (Open Loop) indicates a faulty unit. STEP 3: Check power supply. With ignition ON, check for 12V at one of the harness pins. Check fuses if voltage is absent. STEP 4: Use a diagnostic tool to perform an output/actuator test. Monitor the PWM signal with an oscilloscope at the connector. STEP 5: If wiring and power are OK but the solenoid shows an open circuit, replace the solenoid/turbo actuator.

Powertrain (Engine & Gearbox)Standard EOBD

P0045 - Turbocharger/Supercharger Boost Control Solenoid Circuit / Open

Q: What are the symptoms of fault code P0045?

• Check engine light (MIL) illuminated • Vehicle in Limp Home Mode (Reduced power) • Lack of boost pressure/No turbo spooling sound • Increased fuel consumption • Will cause immediate emission test failure

Last updated:1 February 2026

Related:Turbocharger, VNT Actuator, Engine Control Unit (ECU), Wiring harness, Boost Pressure Sensor (MAP)

System

Powertrain (Engine & Gearbox)

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Technical Description

P0045 is a generic OBD-II diagnostic trouble code which indicates that the Engine Control Unit (ECU) has detected an open circuit in the turbocharger or supercharger boost control solenoid circuit 'A'. This control is typically handled via a Pulse Width Modulated (PWM) signal. The ECU monitors the circuit integrity by checking for continuity and proper current draw. An 'Open Circuit' status means there is a physical break in the wiring, a disconnected plug, or an internal failure within the solenoid coil itself. This will result in the ECU disabling boost control and limiting engine torque (Limp Mode) to prevent mechanical damage from uncontrolled boost levels.

Possible Causes

Faulty turbocharger boost control solenoid/actuator (internal open coil)

Damaged wiring harness or corroded connectors affecting the circuit

Blown fuse for the engine management system (shared power supply)

Faulty Engine Control Unit (ECU) failing to trigger the output driver

Symptoms

Check engine light (MIL) illuminated

Vehicle in Limp Home Mode (Reduced power)

Lack of boost pressure/No turbo spooling sound

Increased fuel consumption

Will cause immediate emission test failure

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P0045 - Turbocharger/Supercharger Boost Control Solenoid Circuit / Open

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P0045 - Turbocharger/Supercharger Boost Control Solenoid Circuit / Open

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