P0039 OBD II Trouble Code Turbo Charger Bypass Valve Control Circuit Range Performance

• A significant reduction in engine performance
• Hissing noises from the turbocharger (and/or hoses) or the supercharger
• Engine and/or transmission temperatures could be higher than normal
• Excessive exhaust system smoke
• Spark plug fouling
• Cylinder detonation, caused by hotter engine temps, are also a possibility
• Other turbocharger boost related codes, engine misfire codes, or knock sensor codes may also be stored

• A shorted/open circuit in the turbocharger bypass control sensor circuit
• The most common cause of a stored P0039 turbo/supercharger bypass valve control circuit range/performance code is probably a defective boost pressure sensor
• A defective turbo/supercharger bypass valve actuator
• Turbo/supercharger bypass valve failure is also fairly common
• Collapsed, disconnected, or split vacuum lines are a possibility (where a vacuum actuated bypass valve is used)
• Loose, corroded, or disconnected electrical wiring/connectors in the turbo/supercharger bypass control/boost pressure sensor reference circuit
• A bad PCM or boost controller

The conditions for causing this code to be stored can lead to major engine damage from excessive turbocharger boost pressure; therefore this code should be treated urgently.