P0299: Turbocharger/Supercharger A Underboost Condition
Actual Manifold Absolute Pressure (MAP) remains significantly below target boost pressure for >4–5 seconds under load.
| Trouble Code (DTC) | P0299 |
|---|---|
| Official SAE Definition | Turbocharger/Supercharger A Underboost Condition |
| Vehicle Subsystem | powertrain |
| Driving Severity | MEDIUM |
Observable Symptoms
- Noticeable loss of power on hills or overtaking
- Limp-home mode engaged
- Whistling or hissing sound under boost
Most Probable Root Causes
- Split charge-air hose or intercooler leak
- Sticking wastegate actuator or torn diverter valve diaphragm
- Faulty N75 boost control solenoid or clogged DPF/catalyst
Step-by-Step Diagnostic Procedure
- Pressure-test charge air cooler (intercooler) tract for boost leaks
- Check wastegate actuator rod travel and vacuum/electronic control