P0045 Turbocharger/supercharger boost control A circuit/open
What P0045 means
The engine computer controls boost by switching a solenoid or electric actuator that operates the wastegate or variable vanes. P0045 means it detected an open circuit or incorrect signal in that control circuit. The car usually limits boost and goes into limp mode.
P0045 is a generic SAE J2012 code: it means the same on every make. The exact cause still depends on the car, so read the freeze-frame data before replacing parts.
At a glance
- Severity
- High
- Typical repair cost
- 80–600 €
- Workshop time
- 0.5–3 h
- Repair difficulty
- Medium
- DIY possible
- Yes
- Check engine light
- Yes
- Affects emissions test
- Yes
- Limp mode possible
- Yes
Parts and labour at an independent workshop in Europe. Main dealers charge more; the cause decides the bill, not the code.
Symptoms
- Check engine light on
- Loss of power or limp mode
- No turbo boost felt
- Overboost on some engines if the wastegate stays closed
Common causes
- Failed boost control solenoid (N75-type valve) or electric actuator
- Broken wire or open circuit
- Corroded or loose connector
- Blown fuse supplying the solenoid
- Engine computer driver fault (rare)
Can I keep driving with P0045?
Drive carefully and get to a workshop soon. Power will be reduced, and on some engines uncontrolled boost can damage the turbo or engine.
What to check first
- Check the connector on the boost control solenoid or actuator
- Measure solenoid resistance and supply voltage
- Check wiring continuity back to the engine computer
- Replace the solenoid or actuator if faulty, then clear codes and test drive
Related codes
- P0038 Oxygen sensor heater control circuit high (bank 1, sensor 2)
- P0037 Oxygen sensor heater control circuit low (bank 1, sensor 2)
- P0036 Oxygen sensor heater control circuit (bank 1, sensor 2)
- P0030 Oxygen sensor heater control circuit (bank 1, sensor 1)
- P0021 Intake (A) camshaft timing over-advanced or system performance (bank 2)
- P0020 Intake (A) camshaft position actuator circuit/open (bank 2)
- P0071 Ambient air temperature sensor range/performance
- P0019 Crankshaft/camshaft position correlation, bank 2 sensor B (exhaust)
Data: TORKO fault-code catalogue, built on OBDex (CC0-1.0) and reviewed against workshop practice. Informational only — it does not replace a diagnosis by a mechanic.
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