P0299: Turbocharger/Supercharger A Underboost Condition

Symptoms

• Significant loss of power, especially on acceleration
• Limp mode kicking in
• Whistling or hissing from the engine bay
• Black smoke under load

Common causes

• Boost or intercooler hose leak
• Faulty wastegate or actuator
• Failing turbocharger
• Clogged intercooler or intake
• Bad boost pressure sensor

What to do?

Inspect every boost pipe and intercooler hose for cracks, splits, and loose clamps - this is the most common cause. Check the wastegate actuator for free movement and proper rod travel. Use a scan tool to compare requested vs actual boost pressure to confirm the underboost.