What Does P0299 Mean?
The turbocharger or supercharger on bank A is not producing the expected level of boost pressure. The ECM has detected that actual boost is significantly below the commanded or expected target. The driver will notice reduced power, sluggish acceleration, possible black smoke, and the engine may enter limp mode. This is a common code on turbocharged gasoline and diesel engines.
Common Causes
30%
Boost pressure leak in intercooler piping, charge pipes, or couplings allowing pressurized air to escape
25%
Wastegate stuck open or actuator diaphragm ruptured, preventing boost buildup
20%
Turbocharger shaft bearing wear or compressor wheel damage reducing boost efficiency
15%
Boost pressure sensor or MAP sensor providing incorrect readings to the ECM
10%
Clogged air filter or restricted exhaust (plugged catalytic converter/DPF) limiting turbo performance
Diagnostic Steps
1
Monitor boost pressure PID and commanded boost PID during a wide-open-throttle acceleration test; compare actual vs. target boost. Typical peak boost varies by application (10-25 psi).
2
Perform a boost leak test using a pressurized adapter on the intake tract (typically 15-20 psi); listen and spray soapy water to find leaks at couplings, intercooler, and charge pipes.
3
Inspect the wastegate actuator operation by applying vacuum/pressure to the actuator and verifying the wastegate arm moves fully and holds position. Typical spec is full stroke at 7-15 psi.
4
Check the turbocharger for shaft play: radial (side-to-side) play should be less than 0.003 inches, and axial (in-out) play should be minimal. Spin the compressor wheel to check for contact with housing.
5
Inspect the air filter for excessive restriction, check the exhaust backpressure (should be less than 2 psi at idle, less than 6-8 psi at full load), and verify no DPF regeneration issues.
6
Test the boost pressure sensor by comparing its reading to a known-accurate mechanical gauge teed into the intake manifold.
Estimated Repair Cost
$100 - $2,500
Parts + labor, varies by vehicle and location
The turbocharger or supercharger on bank A is not producing the expected level of boost pressure. The ECM has detected that actual boost is significantly below the commanded or expected target. The driver will notice reduced power, sluggish acceleration, possible black smoke, and the engine may ente...
The most common cause of P0299 (Turbocharger/Supercharger "A" Underboost Condition) is: Boost pressure leak in intercooler piping, charge pipes, or couplings allowing pressurized air to escape
Typical repair costs for P0299 range from $100 to $2,500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The vehicle can be driven but will have significantly reduced power, which may be dangerous when merging or passing on highways. Avoid heavy load situations. If oil smoke or unusual turbo noise is present, stop driving immediately as turbo failure can send debris into the engine.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0299 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Forced Induction System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
