P0034
PowertrainTurbocharger/Supercharger Bypass Valve Control Circuit Low
The engine control unit has detected an abnormally low voltage reading in the electrical circuit that controls the turbocharger or supercharger bypass valve.
ⓘ Information only. This page provides general educational information about fault code P0034. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does P0034 mean?
P0034 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Turbocharger/Supercharger Bypass Valve Control Circuit Low.
This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
About Turbo / Supercharger codes
Turbo codes report faults in boost pressure, variable-vane mechanisms, wastegates, or boost sensors. On EU diesels, sticking variable vanes from carbon buildup are extremely common at higher mileages.
P0034 is one of 141 codes in this category. Browse all Turbo / Supercharger codes →
What we know about P0034 specifically
We record the SAE J2012 standardised definition and the system this code belongs to, but we have not yet published detailed driver-reported symptoms, common causes, or step-by-step diagnostic guidance for P0034.
Rather than invent that information by generating generic content from a template, we leave it out. For specific guidance, the most reliable sources are:
- •your vehicle's own service manual or manufacturer-specific technical bulletins
- •a qualified mechanic with a manufacturer-level diagnostic tool
- •a marque specialist familiar with your make and model
Codes nearby
Codes adjacent to P0034 in the P-code series. Many fault codes appear together with their neighbours because they relate to the same circuit or component.
Other Turbo / Supercharger codes
Other fault codes in the same system as P0034. The ones with detailed guides have plain-English explanations, symptoms, causes, and diagnostic steps.
Spotted an issue or have something to add? Mechanics, technicians, and drivers who have first-hand experience with P0034 can submit a correction or expansion. We review every submission before publishing, mechanic submissions are prioritised.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →