Powertrain
generic / SAE
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.
SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number2 / 99
Possible causes
- Leak in intercooler pipe or hose high
- VGT vanes stuck (diesel, soot buildup) high
- Wastegate stuck open or weak spring medium
- Turbo bearing worn (preceded by oil consumption / smoke) low
Symptoms
- Check engine light on
- Significant power loss / limp mode
- Possible blue or black smoke from exhaust
- Whistling or hissing sound from intake
Inspection / repair
- Difficulty: hard
- DIY: shop recommended
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References
sae:J2012