OBD-II reference

All 9.533 generic OBD-II codes, explained in detail.

Causes, inspection steps and sources — a comprehensive DIY archive. Created and maintained with love for the detail. Good luck and have fun!

Powertrain generic / SAE

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.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number– / 4A

Possible causes

  • Wiring break high
  • Pin pushed back out of connector body low
  • Cracked solder joint inside the module or sensor low

Symptoms

  • Charge status indicator shows fault
  • Charging may not start or interrupts
  • Slower-than-expected charge rate

Inspection / repair

  • Difficulty: medium
  • DIY: possible
  • Estimated cost: 80–600 €
  • Estimated time: 0.5–3 h
  • Component: boost control solenoid b
  • Component: actuator wiring
  • MIL / check engine light
  • emissions-relevant
  • drive cycle required
  • limp mode possible

Sources

References

How to read OBD-II codes

The first letter names the vehicle system, the second digit distinguishes generic from manufacturer-specific, the remaining digits group fault area and number.

PPowertrain: engine, transmission, emissions
BBody: chassis trim, comfort, interior
CChassis: suspension, brakes, steering
UNetwork: CAN, control modules, communication