Fuel and air

P0045 — Turbo/Supercharger Boost Control 'A' Circuit Open

Severity: medium Drive with care, to a shop

What P0045 means

The engine computer regulates boost with a control solenoid or an electric vane actuator, and it monitors the electrical circuit of that device. P0045 sets when the 'A' circuit reads open or has abnormally high resistance, so the ECM cannot control boost reliably. Wiring, connector or solenoid problems are the most common reasons.

Symptoms

  • Check Engine light on
  • Reduced power and sluggish acceleration
  • Limp mode
  • No boost or erratic boost
  • Unusual noises from the turbo
  • Worse fuel economy

Possible causes

  1. Open circuit or poor contact in the boost solenoid wiring
  2. Corroded or damaged solenoid connector
  3. Failed boost control solenoid or vane actuator
  4. Faulty actuator position or boost pressure sensor
  5. Cracked or disconnected vacuum lines (on vacuum-operated systems)
  6. Failed ECM (rare)

How to diagnose

  1. Scan all codes and freeze frame data, clear the code and see if it returns
  2. Inspect the solenoid harness and connector for chafing, oil, moisture and corrosion
  3. Check vacuum hoses and lines for cracks or disconnection on vacuum-type systems
  4. Measure solenoid coil resistance and compare it with the service spec
  5. Check power and ground at the connector and test wire continuity back to the ECM
  6. Command the actuator with a scan tool and confirm it moves through its full range
  7. Compare specified and actual boost in live data
  8. If all is fine, test the boost pressure sensor before suspecting the ECM

Common fixes

  • Repair the wire or replace the damaged connector
  • Replace the boost control solenoid or electric actuator
  • Replace the position or boost pressure sensor
  • Replace damaged vacuum hoses
  • Reflash or replace the ECM (last resort)

Questions and answers

What does P0045 mean?

It means an open circuit in the turbo boost control 'A' circuit. The ECM can't see a proper electrical circuit to the solenoid or actuator, so it can't regulate boost accurately.

Can I drive with P0045?

Briefly and carefully, for example to a shop. Power is usually limited, and uncontrolled boost can harm the turbo and engine.

How do I fix P0045?

Start with the wiring and connector at the boost solenoid, then test the solenoid resistance and actuator movement. Repairing the wiring or replacing the solenoid fixes most cases.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.