P0299

Turbocharger/Supercharger A Underboost Condition

Car Fault Codes Fuel & air

Can you still drive? With care, short trips only

Who can fix it? Needs a workshop

Typical repair time 30 minutes – 10 hours

Typical cost SAR 100 to 9,000

What it means

The engine computer has detected that actual boost pressure from the turbocharger or supercharger is lower than the requested pressure for a set period. The most common cause is a leak in the pressurized air hoses or a wastegate control fault, and the engine may enter limp mode with a clear loss of power.

Symptoms4

Clear loss of power and slow acceleration.
Engine goes into limp mode, limiting speed or RPM.
Whistling or air hissing from the turbo or its hoses during acceleration.
Check engine light on, and possibly black smoke on diesel engines.

Possible causes7

Leak in the boost hoses or intercooler, or a loose clamp.
Faulty wastegate, boost control solenoid or their vacuum hoses.
Clogged air filter or air intake.
Faulty boost pressure sensor or circuit reading lower than actual pressure.
Exhaust leak ahead of the turbocharger.
Blocked diesel particulate filter (DPF) or catalytic converter restricting exhaust flow.
Worn turbocharger or sticking variable geometry vanes.

How to diagnose6

Read all codes and watch desired versus actual boost pressure on a scan tool during acceleration.
Inspect the boost hoses, intercooler and clamps for cracks or oily residue, or perform a pressure or smoke leak test.
Check the air filter and air intake.
Test wastegate or variable vane movement, and check the control solenoid and its vacuum hoses.
Compare the boost pressure sensor reading with barometric pressure with the engine off.
Check the turbocharger for excessive shaft play or damaged blades, and make sure the exhaust is not restricted.

How to fix6

Tighten the loose clamp or replace the cracked hose.
Replace the air filter if it is clogged.
Replace the boost control solenoid, its hoses or the boost pressure sensor based on test results.
Repair the wastegate or variable vane mechanism, and clean or replace the DPF if it is blocked.
Replace the turbocharger if it is proven faulty, and find the cause of the failure, such as poor turbo lubrication.
Clear the codes, then road test under load and confirm actual boost matches the requested boost.

Repair cost

0–500

500–2,000

2,000–5,000

5,000+

In Saudi riyals; the highlighted part is the expected range for this fault.

The cost is low when a loose clamp or cracked hose is to blame, and rises sharply when a new turbocharger is needed.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions

Does P0299 mean the turbo is bad?

Usually not. The most common causes are a boost hose leak or a wastegate control problem, and the turbo should only be replaced after ruling them out.

Can I drive with this code?

You can drive gently for short distances, but stop if you hear metallic scraping, see blue smoke or notice oil loss, because the turbo may be damaged internally.

Why does the code sometimes appear only in hot weather or at high altitude?

Hot or thin air makes the turbo work close to its limit, so a small leak or weak boost control only shows up under those conditions.

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This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.

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