P0299 Turbocharger/supercharger A underboost
What P0299 means
The engine computer compares the boost pressure it commands with the pressure measured in the intake. P0299 means actual boost stayed too low. Usually the car goes into limp mode with a clear loss of power to protect the engine.
P0299 is a generic SAE J2012 code: it means the same on every make. The exact cause still depends on the car, so read the freeze-frame data before replacing parts.
At a glance
- Severity
- High
- Typical repair cost
- 100–1500 €
- Workshop time
- 0.5–10 h
- Repair difficulty
- Hard
- DIY possible
- No
- Check engine light
- Yes
- Affects emissions test
- Yes
- Limp mode possible
- Yes
Parts and labour at an independent workshop in Europe. Main dealers charge more; the cause decides the bill, not the code.
Symptoms
- Check engine light on
- Sudden loss of power or limp mode
- Hissing or whistling from the engine bay under load
- Black or blue smoke from the exhaust
Common causes
- Split, loose or oil-soaked boost hose or intercooler leak
- Sticking variable-vane (VNT) mechanism or wastegate
- Faulty boost control solenoid or vacuum hose
- Faulty boost pressure sensor
- Worn turbocharger, or restricted exhaust such as a blocked DPF
Can I keep driving with P0299?
Have it checked today or tomorrow. Power will be limited, and if the turbo itself is failing, continued driving can cause further damage.
What to check first
- Inspect all boost hoses, clamps and the intercooler for splits or oil residue
- Compare commanded and actual boost in live data during acceleration
- Check vacuum hoses and the boost control solenoid; check the wastegate or VNT actuator moves freely
- Check exhaust back-pressure (DPF) and turbo shaft play before replacing the turbo
Related codes
- P0270 Cylinder 4 injector A circuit low
- P0269 Cylinder 3 contribution/balance fault
- P0267 Cylinder 3 injector A circuit low
- P0264 Cylinder 2 injector A circuit low
- P02D1 Cylinder 3 fuel injector offset learning at maximum limit
- P0261 Cylinder 1 injector A circuit low
- P024E Charge air cooler bypass position sensor A circuit low
- P02ED Diesel intake air flow control system, low air flow detected
Data: TORKO fault-code catalogue, built on OBDex (CC0-1.0) and reviewed against workshop practice. Informational only — it does not replace a diagnosis by a mechanic.
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