Code 4-2-1 (Pressure Sensor Signal)
- This is a mechanical check of turbo control valve. Disconnect hoses from valve. With control valve in rest position, blow air through fitting that connects to intake manifold. Air should come out through fitting that connects to pressure regulator.
- Apply 12 volts to control valve. Blow air through fitting that connects to intake manifold. Air should come out through fitting that connects to pressure regulator and to intake side of turbo. Replace control valve as necessary.