P0299
P0299 Turbo/Supercharger Underboost
P0299 is a generic OBD2 powertrain diagnostic trouble code for turbo/supercharger underboost. The code identifies the system or circuit the engine computer flagged, but diagnosis still depends on vehicle symptoms, freeze-frame data, and related codes.
How urgent is P0299?
Boost-control codes can cause limp mode and poor power. Avoid hard acceleration until the boost leak or control issue is diagnosed.
Common symptoms
- Check engine light
- Low power
- Limp mode
- Whistling or hissing under boost
- Smoke under acceleration
Likely causes
- Boost leak
- Wastegate or bypass valve issue
- Turbo control solenoid fault
- MAP/boost sensor issue
- Restricted intake or exhaust
What to check before replacing parts
1
Pressure-test intake/charge pipes
2
Inspect vacuum/boost hoses
3
Check wastegate or actuator movement
4
Compare commanded vs actual boost
5
Inspect boost sensor data
Use the code with symptoms
A code points at the system, not always the failed part. Add your vehicle, mileage, symptoms, and whether the check engine light is steady or flashing so the AI diagnostic can narrow the next step.