OBD-II code · Powertrain (generic)
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.
Is it safe to drive with P004A?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyWiring break
- Less likelyPin pushed back out of connector body
- Less likelyCracked solder joint inside the module or sensor
Symptoms
- Charge status indicator shows fault
- Charging may not start or interrupts
- Slower-than-expected charge rate
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–3 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Boost Control Solenoid B, Actuator Wiring
Related codes
- P0045Turbocharger/Supercharger Boost Control A Circuit/Open
- P0047Turbocharger/Supercharger Boost Control A Circuit Low
- P0048Turbocharger/Supercharger Boost Control A Circuit High
- P0049Turbocharger/Supercharger A Turbine Overspeed
- P004BTurbocharger/Supercharger Boost Control B Circuit Range/Performance
- P004CTurbocharger/Supercharger Boost Control B Circuit Low
- P004DTurbocharger/Supercharger Boost Control B Circuit High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.