P0034 Code: Turbocharger/Supercharger Bypass Valve “A” Control Circuit Low

Reviewed by

Richard McCuistian, ASE Certified Master Automobile Technician

Technical Reviewer at CarParts.com

Written by CarParts.com Research Team - Updated on June 26th, 2024

Reading Time: 5 minutes
Summary
  • The P0034 code is logged once the PCM senses an issue with the turbocharger, the supercharger bypass valve, or its control circuit.
  • The possible triggers of this error code include a bad turbocharger, an issue with the PC, and circuit issues.
  • Common symptoms of this error code include foreign noises from the bypass valve and poor engine performance.

On-board diagnostic (OBD) codes are designed to help identify potential issues perceived by the vehicle’s primary computer. Connecting a scan tool or code reader to the vehicle’s OBD port will allow you to retrieve error codes that have been logged in the system. To resolve them, you must first know what each code means.

One of the codes you may come across is the P0034 code. Read on to learn more about what it means and how you may resolve this code.

What Does the P0034 Code Mean?

Diagnostic trouble code (DTC) P0034 stands for “Turbocharger/Supercharger Bypass Valve “A” Control Circuit Low.” This engine code is stored when the powertrain control module (PCM) perceives an issue with the turbocharger (or supercharger) bypass valve or its control circuit.

Turbocharged engines have a bypass valve that prevents excessive pressure from building up and traveling back to the turbo’s compressor.

Turbocharged engines have a bypass valve (also known as a compressor bypass valve). When the throttle is closed rapidly, the bypass valve quietly prevents excess pressure from building up and traveling back to the turbo’s compressor.

Supercharged engines also have a bypass valve. In a supercharged engine, the bypass valve is used to control boost pressure by routing air directly to the intake manifold.

On most vehicles, the bypass valve is controlled by the PCM. When the PCM detects a problem with the bypass valve or the valve’s control circuit, it may set code P0034.

Depending on the severity of the problem, the PCM may also store other related diagnostic trouble codes. Related DTCs include codes P0033, P0035, P0234, and P0235.

You can read our technical discussion about turbochargers and superchargers for more information that could help you resolve code P0034.

Note: The definition of code P0034 may be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

What are the Possible Causes of the P0034 Code?

Here are some common triggers of the error code P0034:

  • Faulty turbocharger/supercharger bypass valve
  • Circuit issues (damaged wires or poor connections)
  • An issue with the PCM (software in need of an update)

What are the Common Symptoms of the P0034 Code?

The following symptoms below are commonly associated with the P0034 trouble code:

How to Diagnose the P0034 Code

Trouble code P0034 is a generic code, which means it may appear across several makes and models.

Trouble code P0034 is a generic code, which means it may appear across several makes and models. However, the steps for troubleshooting this code will vary depending on the vehicle’s make and model.

As this is a complicated code, it is best to refer to your repair manual for diagnostic strategies. If you’re not well-versed in auto repair, leaving the diagnosis to a professional is your best option.

How to Fix the P0034 Code

P0034 shares similar triggers and symptoms with several error codes. However, there is no generic fix to resolve this code. For example, known fixes for a P0034 code in a Mercedes may be different from the repair procedures for a Chrysler P0034 code. It’s best to leave this matter to the experts if you aren’t confident in your automotive repair skills.

All vehicles are different, so do your research thoroughly before working on a solution for this code. Always refer to your vehicle’s repair manual before attempting any DIY repairs. You may also get detailed factory repair information from an online repair database.

Where to Get a New Turbocharger for Your Automobile

As mentioned, issues with the turbocharger could lead to the P0034 code being logged by the vehicle computer. Luckily, CarParts.com makes finding replacement auto parts and accessories a breeze.

Find the right parts for your vehicle with just a few clicks. Just visit our website or download our mobile app to shop for high-quality yet affordable parts for your ride. Use our vehicle selector to check for fitment, and toggle our search filters to shop according to your preferred brand or price range.

All products are on hand and ready to ship from a distribution center near you. If you place your order before noon ET, you could get your package in as fast as two business days.

Shop and order a high-quality turbocharger for your vehicle today!

Products Mentioned in this Guide

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Replacement – New Turbocharger
$331.99 Price and rating may change from the time content is published.
Mopar® – 68190237AB Supercharger Kit – Direct Fit
$552.49 Price and rating may change from the time content is published.
About The Authors
Reviewed By Richard McCuistian, ASE Certified Master Automobile Technician

Technical Reviewer at CarParts.com

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Written By CarParts.com Research Team

Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

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