P0299Diesel & RV
HardP0299 — Turbocharger underboost
Boost pressure is below the commanded target. The engine loses power—especially under load or climbing—a common complaint on highway diesels.
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Likely causes
- Boost leak between the turbo and intake (hoses, intercooler)
- Stuck/fouled wastegate actuator or VGT vane
- Worn turbo (bearing play or damaged compressor wheel)
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Recommended checks
- 1
Smoke-test or pressure-test the charge-air system
- 2
Clean or replace the VGT/wastegate actuator
- 3
Check turbo axial/radial play and replace if needed
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Parts to replace
Turbo boost hose
VGT actuator
Turbocharger