Boost · Severity: Moderate
P0299 — Turbocharger/Supercharger A Underboost
Measured boost pressure is below the value requested by the ECU.
Common symptoms
- Loss of power
- Limp mode
- Whistling under load
- Black smoke (diesel)
Likely causes
- Split or loose boost hose/intercooler
- Sticking VGT vanes or wastegate
- Faulty boost control solenoid
- Worn turbocharger
- Restricted exhaust or DPF
First test to run
Smoke-test the intake and boost pipes, then log commanded vs. actual boost during a full-load pull.
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