P0299 and P0234: turbo or supercharger boost
The boost pressure is lower than the engine computer asked for (P0299), or higher than it allows (P0234).
SeverityModerateUsually not urgent today, but it can get worse if left.
Can you keep driving?Drive gently, check it soonWhat does P0299 mean?
The computer sets a target boost from the load and engine speed and reads the real value from the boost sensor. A gap that lasts too long is stored as underboost or overboost, and most engines then limit power to protect themselves. Underboost is far more common, and it is usually a leak or a sticking control part rather than a failed turbocharger.
What causes P0299?
- A split intercooler hose or a loose clamp
- A wastegate or variable vane mechanism that sticks, often with soot on diesels
- A faulty boost control solenoid or its vacuum lines
- A faulty boost pressure sensor
- A worn turbocharger, or a blocked air filter or particulate filter
What to check first for P0299
- Check the intercooler hoses and clamps for splits and oil
- Listen for a whistle or a hiss under load
- Compare target and actual boost on a scan tool during a road test
- Check the vacuum lines to the actuator
Can you drive with P0299?
Usually safe to drive gently to a workshop on reduced power. If you see blue smoke, hear a siren-like whine or a grinding noise, or the oil level drops, stop: the turbocharger may be failing.
In states with an OBD-II emissions inspection, a car with the check engine light on fails the test until the fault is fixed.
Codes on this page
- P0299Turbo/Super Charger Underboost
- P0234Turbo/Super Charger Overboost Condition
Related codes
Checked on · Rafael Soares
These are the generic meanings every manufacturer shares. Each brand adds its own detail, so your car's handbook, its service information and a qualified mechanic have the last word. OdoKeep has no connection with any manufacturer, and the app does not read codes from the car.
