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DTC codes / P00xx · Fuel and air metering and auxiliary emission controls / P0045

P0045Turbo/Super Charger Boost Control Solenoid Circuit/Open

P0045 means the engine computer has detected an open circuit or excessive resistance in the wiring for the turbocharger or supercharger boost control solenoid. The computer commands the solenoid to regulate boost pressure, but the electrical feedback does not match the expected current, so it flags the circuit as open.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering and auxiliary emission controls

Symptoms you may notice

  • Illuminated check engine light, often with no other noticeable symptoms
  • Reduced engine power or limp mode when boost pressure is limited
  • Poor acceleration and sluggish throttle response
  • Decreased fuel economy due to the engine running without proper boost control
  • Possible turbo overboost or underboost symptoms if the solenoid fails to regulate pressure
  • Rough running or hesitation under load in some cases

Common causes, most likely first

  1. Broken, chafed, or disconnected wires in the boost control solenoid circuit
  2. Corroded or loose electrical connector at the solenoid or at the engine computer
  3. Failed boost control solenoid (open coil or seized internally)
  4. Blown fuse or faulty relay supplying power to the solenoid circuit
  5. Engine computer driver failure for the solenoid control circuit (rare)
  6. Aftermarket wiring modifications or poor previous repairs causing an open circuit

How to diagnose and fix it

  1. Scan all modules and record freeze-frame data to confirm P0045 is the only boost-related code
  2. Visually inspect the solenoid connector and wiring harness for damage, corrosion, or loose pins
  3. Measure resistance across the solenoid coil and compare to the manufacturer's specification
  4. Check for battery voltage at the solenoid connector with the key on, and verify the ground path
  5. Perform a wiggle test on the harness while monitoring solenoid resistance or a test light
  6. If wiring and solenoid test good, check continuity from the solenoid to the engine computer and inspect computer pins
  7. Replace the faulty solenoid or repair the open wiring, clear codes, and verify boost control operation with a road test

What P0045 does not always mean

  • A P0045 does not automatically condemn the boost control solenoid; a simple unplugged connector or a broken wire is just as common.
  • Some vehicles use a vacuum-operated wastegate solenoid that is electrically identical to a boost control solenoid, so the same code can appear on turbo and supercharged engines alike.
  • A failed solenoid can cause the turbo to overboost and set a separate overboost code, so ignoring P0045 may lead to more expensive damage.
  • The engine computer may command the solenoid to a default position when the circuit is open, which can mask driveability symptoms until the driver demands full power.
  • Corrosion inside the solenoid connector often looks like a failed solenoid, so always back-probe and load-test the circuit before replacing parts.

Can I keep driving with P0045?

You can usually drive the vehicle with P0045, but avoid heavy throttle and towing until the fault is repaired because boost control is compromised. Prolonged driving with an open solenoid circuit can lead to overboost conditions that damage the turbocharger or engine.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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