P003B
Turbocharger/Supercharger Boost Control B Position Exceeded Learning Limit
Forced induction (turbo/super)
Generic OBD-II
High
What it means
P003B means the "B" turbo/supercharger boost-control actuator has moved so far out of its calibrated position that the engine control module can no longer compensate through its learned adaptation. It usually points to a sticking or worn wastegate/actuator, binding linkage, or a drifting position sensor rather than a wiring break. Expect reduced boost and power.
High
Can I keep driving? Drivable but down on power and may enter limp mode; the mechanical actuator problem can worsen, so have the wastegate/actuator inspected soon.
Common symptoms
What you'll notice
- Check-engine light on
- Reduced boost and power
- Reduced-power / limp mode
- Over- or under-boost behavior
- Reduced fuel economy
Common causes
Most likely first
- Sticking or binding wastegate / boost-control actuator (mechanical)Likely
- Worn or misadjusted actuator linkage or rodCommon
- Carbon buildup on variable-geometry vanes (VGT)Common
- Drifting boost-control actuator position sensorLess often
- Boost or vacuum line leakLess often
- Wiring fault (less common for a learning-limit code)Less often
How to diagnose & fix
Work through it in order
- Scan and record freeze-frame data.
- Inspect the wastegate/actuator for free movement and correct rod adjustment.
- On VGT turbos, check the vanes for carbon binding.
- Test the actuator position sensor and its wiring.
- Check boost and vacuum lines for leaks, then perform the actuator relearn after repair. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P003B?+
Short-term yes, but expect reduced power and possible limp mode. The actuator has drifted beyond what the computer can compensate for, so a mechanical inspection is due.
Can I just clear P003B?+
It will return because the actuator position is genuinely out of range — you need to free up or adjust the wastegate/actuator and relearn it, not just clear the code.
Related codes
Often seen with P003B
Read & clear P003B yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX