For 1990-2009 cars

Condition | Action
--- | ---
Some whine noise is normal. Compare to a known good vehicle.
Leaking charge air cooler/pipes/hoses | Inspect for leaks in charge air cooler/pipes/hoses.
Worn turbocharger bearings |

• | Inspect the turbocharger bearings. Refer to Turbocharger Lack of Oil Supply .

• | If the turbocharger bearings are worn or damaged, repair or replace the turbocharger.

Intake system leaks or obstructions | Inspect for leaks or obstructions in the intake manifolds.