P0045: Turbocharger/Supercharger Boost Control A Circuit/Open
What to do
Expect a marked loss of power, possibly a limp mode. Drive gently and have it diagnosed promptly rather than pressing on.
What this code means
An open circuit in the solenoid that regulates boost pressure — the valve that bleeds control pressure to the wastegate actuator or commands a variable-geometry turbocharger's vane position. Losing control of boost is not a small fault: depending on the design, the engine either falls back to minimum boost and feels flat, or loses its ability to limit boost and risks overpressure. Most modules choose the safe option and cut power.
Likely causes
Start here
- Failed boost control solenoid · moderate
- Open circuit in solenoid wiring · moderate
- Corroded or loose connector · easy
Less common
Rare
- Control module driver failure · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
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