OBD-II code · Powertrain (generic)
P0299 Turbocharger/Supercharger "A" Underboost Condition
Boost pressure under load is below the commanded value. Very common on turbodiesel and direct-injection turbo gasoline engines as the turbo system ages — typically a leaking boost pipe, a sticky variable-geometry vane assembly, or a wastegate that no longer holds.
Is it safe to drive with P0299?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyLeak in intercooler pipe or hose
- Most likelyVGT vanes stuck (diesel, soot buildup)
- PossibleWastegate stuck open or weak spring
- Less likelyTurbo bearing worn (preceded by oil consumption / smoke)
Symptoms
- Check engine light on
- Significant power loss / limp mode
- Possible blue or black smoke from exhaust
- Whistling or hissing sound from intake
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–10 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Turbocharger, Intercooler, Intercooler Pipe, Wastegate Actuator, Vgt Actuator
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.