The electric boost actuator B positions the variable turbine vanes or the wastegate and reports its position through a sensor. In a learning run, for example with the engine warm at idle or after switching off, the control module drives the actuator to its mechanical end stops and stores the sensor values as reference. P003B is set when a learned end position or the total travel lies outside the permitted limits. Typical reasons are worn or sticking vanes or linkage, a faulty actuator, a broken actuator lever, or a replacement actuator that has not been learned in. B denotes the second actuator, for example on the second stage of a two-stage system.
Medium severity. Can I keep driving?Drive without demanding power and go to a repair shop soon. If you see a lot of blue smoke or hear a metallic noise, shut off the engine.
Symptoms
- Check engine light on
- Reduced power mode
- Underboost or overboost codes possible
- Sometimes no noticeable symptoms
Most likely causes
- Electronic actuator or its control module faulty
- Vane mechanism, sector gear or linkage worn or sticking
- Replacement not learned in, or learning run aborted (e.g. low voltage)
- Actuator lever broken
- Position sensor or its wiring faulty
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- It can trigger limp mode.
- It affects emissions.
What each character of P003B means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 0: Subsystem depends on the code range
- 3B: Specific fault in that system
Frequently asked questions
Can I keep driving with code P003B?
Drive without demanding power and go to a repair shop soon. If you see a lot of blue smoke or hear a metallic noise, shut off the engine.
What causes code P003B?
The most common causes are: electronic actuator or its control module faulty; vane mechanism, sector gear or linkage worn or sticking; replacement not learned in, or learning run aborted (e.g. low voltage).
Related codes
- P003ATurbocharger/Supercharger Boost Control A Position Exceeded Learning Limit
- P004ATurbocharger/Supercharger Boost Control B Circuit/Open
- P004BTurbocharger/Supercharger Boost Control B Circuit Range/Performance
- P2587Turbocharger Boost Control Position Sensor B Circuit Range/Performance
- P0234Turbocharger/Supercharger A Overboost Condition
- P0299Turbocharger/Supercharger A Underboost Condition
Sources
- law.cornell.edu: 13 CCR 1968.2
- saabwisonline.com: dtc p003a lby
- gsi.ext.gm.com: 18OBDG04 Engine Diagnostics
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.