P004A
Turbocharger/Supercharger Boost Control B Circuit/Open
Open circuit at boost control solenoid B (twin-turbo or two-stage system). Same diagnosis as P0045 on actuator B.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Symptoms
- Charge status indicator shows fault
- Charging may not start or interrupts
- Slower-than-expected charge rate
Common causes
Ordered by how often each turns out to be the cause.
- Wiring breakCommon
- Pin pushed back out of connector bodyLess likely
- Cracked solder joint inside the module or sensorLess likely
Parts involved
- Boost Control Solenoid B
- Actuator Wiring
P004A is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.