Error P0033: This fault code applies to all car manufacturers and means “Turbocharger/Supercharger Bypass Valve Control Circuit“.
Background Information: A turbocharger uses the inertial force of exhaust gases from the engine to drive a turbine, which in turn drives a coaxial impeller to pressurize the intake air, thereby increasing the vehicle’s power. A supercharger is an air compressor used to increase the intake air of an internal combustion engine. More intake air provides the engine with more oxygen, allowing the control module to deliver more fuel, thus increasing output power. The supercharger bypass valve’s function is to open when the boost pressure is too high, releasing some of the high-pressure air to protect the supercharger and engine. This fault code indicates that the voltage in the turbocharger/supercharger bypass valve control circuit is outside the calibrated normal range.
Causes of the P0033 fault code include: Turbocharger bypass valve actuator failure; Turbocharger bypass valve failure; Disconnected, cracked, or collapsed vacuum line (vacuum-driven bypass valve); Boost pressure sensor failure; Short circuit or open circuit in the boost sensor circuit; Loose, corroded, or disconnected electrical connectors in the boost sensor reference circuit; Defective PCM or boost controller.
Symptoms of the P0033 fault code may include: Degraded engine performance; Buzzing or clicking sounds from the turbocharger or turbo exhaust pipe; Excessive exhaust smoke; Spark plug entanglement; Increased engine and/or transmission temperature; Abnormal hissing sounds from the turbocharger wastegate valve and/or hoses. Additional codes may also be stored, including turbocharger-related codes, engine misfire codes, or knock sensor codes. Cylinder knock is also a significant possibility due to increased engine temperature. If applicable, the boost pressure gauge may also show abnormal boost pressure levels.
Important! Ignoring this error could lead to turbocharger overload, which could be critical. Continuous driving with a P0033 error increases the risk of intake system damage and overall engine performance degradation.
How to Diagnose a P0033 Error (Step-by-Step Instructions)
- Step 1: Connect an OBD2 scanner to confirm the presence of the P0033 fault code.
- Step 2: Visually inspect the BOV valve and connector for damage or corrosion.
- Step 3: Use a multimeter to test the valve resistance (typically 20 to 40 ohms).
- Step 4: Check the connector power supply – ensure the voltage is coming from the ECU. Perform a valve activation test using a diagnostic scanner (if supported).
Required Tools: OBD2 scanner, multimeter, dielectric grease, automotive wiring diagram
How to Fix a P0033 Fault Code?
Here are possible solutions to this problem:
- If the pressure is within the correct range as indicated by the manufacturer, the pressure sensor is the problem.
- Perform a pressure test between the turbocharger and the intake throttle body to ensure the pressure is correct. This will show whether the manufacturer-set pressure is too low or too high.
- If the pressure is too high, check the bypass valve for a fault and ensure it opens at the maximum boost pressure as required by the manufacturer. This usually requires replacing the valves or actuators in the diaphragm system.
- If the pressure is too low, check the intake hose, intercooler, piping, and clamps for cracks or looseness. If they are working properly, check if the bypass valve is slightly or fully open.
