P0299

What it means

P0299 means the engine control unit has seen the actual boost pressure stay below the target boost pressure for longer than it allows. The comparison is normally made using the manifold pressure or boost pressure sensor reading against the commanded value. The cause can be a boost leak, a faulty boost control device or a restriction, and the details depend on the engine and turbo type.

Symptoms

• Noticeable loss of power, especially under load or when accelerating
• Engine warning light on, sometimes with limp mode active
• Turbo whistling, hissing or fluttering noises, or no turbo noise at all
• Black or blue smoke from the exhaust in some cases
• Poor fuel economy and sluggish response
• Slow or lazy throttle response when overtaking or climbing hills

Possible causes

• Boost leak from a split or loose charge air hose, clamp, intercooler or intake jointlikely
• Faulty or sticking boost control: wastegate actuator, variable geometry vane mechanism or electronic control valve/solenoidlikely
• Leaking, blocked or disconnected vacuum or pressure lines to the actuator (where fitted)possible
• Faulty boost or manifold pressure sensor giving a false reading, or wiring and connector fault on itpossible
• Restricted air intake or exhaust, such as a blocked air filter, clogged particulate filter or damaged catalytic converterpossible
• Worn or damaged turbocharger (shaft play, damaged compressor or turbine wheel, oil contamination)possible
• Exhaust leak ahead of the turbine, reducing the energy that drives the turborare

How to diagnose

1. Read the stored and pending codes and the freeze frame data, noting load, engine speed and boost at the time the fault was set, and check for related codes such as sensor or actuator faults
2. Visually inspect the air filter, intake pipework, intercooler and all clamps and connectors for splits, oil residue, looseness or damage
3. Check the wiring and connectors to the boost pressure sensor and the boost control actuator or solenoid for damage, corrosion or poor contact
4. Compare live data for requested and actual boost, and check the pressure sensor reading with the engine off against ambient pressure
5. Test the actuator operation using the manufacturer's procedure, and check that the wastegate or vane mechanism moves freely and fully
6. Pressure test the charge air system for leaks and check vacuum or pressure lines to the actuator where fitted
7. Check for exhaust leaks and restrictions, including the particulate filter and catalytic converter condition, using back pressure or live data as the model allows
8. Inspect the turbocharger for shaft play, oil leakage and wheel damage once the other causes have been ruled out

How to fix

• Replace or refit split hoses, damaged intercooler parts and loose clamps to restore a sealed charge air system
• Repair or replace the faulty boost control solenoid, wastegate actuator or variable geometry mechanism as diagnosed
• Replace perforated or blocked vacuum or pressure lines and secure connections
• Replace a faulty boost pressure sensor or repair its wiring and connector
• Replace a blocked air filter and rectify exhaust restrictions or leaks through proper repair or replacement of the affected parts
• Repair or replace the turbocharger if it is worn or damaged, and find out why it failed, such as oil supply or contamination, before fitting a new one

Can I keep driving?

Nearby codes

• P0298GenericEngine Oil Over Temperature
• P029AGenericCylinder 1 - Fuel Trim at Max Limit