P0035 Turbo charger bypass valve control circuit high

P0035 is a generic OBD-II powertrain code that applies to all vehicles (1996-newer) with a turbocharged engine12. The code definition is: P0035 Turbocharger / Supercharger Bypass Valve Control Circuit High

What It Means and How to Fix It

If you have a vehicle with a turbocharged engine, you may encounter the diagnostic trouble code (DTC) P0035. This code indicates that there is a problem with the circuit that controls the turbocharger bypass valve, which regulates the amount of air that goes into the engine. In this article, we will explain the causes, symptoms, and solutions for this code.

The turbocharger bypass valve is a device that opens or closes to adjust the boost pressure, which is the pressure of the air that enters the engine. When the engine needs more power, the turbocharger spins faster and produces more boost pressure. When the engine needs less power, the turbocharger spins slower and produces less boost pressure. The turbocharger bypass valve helps to maintain the optimal boost pressure for different engine conditions.

The turbocharger bypass valve is controlled by an electronic actuator and a sensor. The actuator moves the valve according to the commands from the powertrain control module (PCM). The sensor measures the position of the valve and sends feedback to the PCM. The PCM monitors various engine sensors to calculate and command the desired position of the valve.

The PCM sets P0035 when it detects a high voltage signal in the circuit that controls the turbocharger bypass valve. This could mean that the circuit has a short to power, a low resistance, or a high voltage. 

What are Some Other Codes Related to P0035?

• P0033 Turbocharger / Supercharger Bypass Valve Control Circuit
  
• P0034 Turbocharger / Supercharger Bypass Valve Control Circuit Low
• P0234 Turbocharger Boost Sensor A Circuit Low
• P0235 Turbocharger Boost Sensor A Circuit High
• P0294 Turbocharger Underboost Condition
• P0299 Turbocharger Overboost Condition

These codes indicate more specific problems with the turbocharger bypass valve control circuit or the turbocharger system. 

What are Some Possible Causes of P0035?

• Faulty turbocharger bypass valve: The valve may be stuck, damaged, or leaking, causing it to not move or seal properly. 
  
• Faulty turbocharger bypass valve actuator: The actuator may be defective, causing it to not move or respond to the PCM’s commands. 
• Problem with the wiring or connector for the turbocharger bypass valve actuator: The wiring or connector may be damaged, corroded, or loose, causing a loss of communication or voltage in the circuit. 
• Problem with the PCM: The PCM may be malfunctioning, causing it to send an incorrect or no signal to the actuator. 

What are Some Common Symptoms of P0035?

The symptoms of P0035 may vary depending on the severity and cause of the problem. Some of the common symptoms are:

• Check engine light on: The PCM will turn on the check engine light when it sets the code.
• Decreased engine power and efficiency: If the bypass valve is not working properly, it may affect the boost pressure and the air-fuel ratio in the engine. This may result in lower power, acceleration, and fuel economy.
• Overboosting or underboosting: If the bypass valve is not working properly, it may cause too much or too little boost pressure in the engine. This may cause damage to the engine components or affect the engine performance.
• Stalling: If the bypass valve is not working properly, it may cause too much or too little air to enter the engine, resulting in unstable idle or stalling.
• Squealing or clanking sounds from the turbocharger or turbo pipes: If the bypass valve is stuck, damaged, or leaking, it may cause abnormal sounds from the turbocharger or the turbo pipes due to excessive or insufficient boost pressure.
• Heavy smoke emission from the tailpipe: If the bypass valve is not working properly, it may cause too much or too little fuel to enter the engine, resulting in incomplete combustion and increased emissions. This may produce heavy smoke from the tailpipe, especially black smoke.

Additional codes may also be stored, including turbocharger boost related codes, engine misfire codes, or knock sensor codes. These codes indicate more specific problems with the turbocharger system, engine performance, or engine detonation. 

If applicable, the boost pressure gauge may also show abnormal levels of boost pressure. This may indicate that the bypass valve is not regulating the boost pressure correctly. 

How to Fix P0035?

To fix P0035, you will need a scan tool, a digital multimeter, and a repair manual for your specific vehicle make and model. The following steps are general guidelines for diagnosing and fixing this code. You should always consult your repair manual for more detailed instructions and specifications.

1. Scan your vehicle for codes. Use a scan tool to retrieve any stored codes and freeze frame data from your vehicle’s PCM. Note down any codes and their definitions, as well as any relevant information from the freeze frame data, such as engine speed, load, temperature, etc. Clear the codes and test drive your vehicle to see if they return.
2. Inspect the turbocharger bypass valve and its components. Visually inspect the bypass valve, its actuator, its sensor, and its wiring and connectors for any signs of damage, wear, corrosion, or loose connections. Check for any leaks in the bypass valve or its hoses. Replace any faulty parts as needed.
3. Test the turbocharger bypass valve actuator. Disconnect its electrical connector and use a digital multimeter to check for resistance across its terminals. Compare your reading with your repair manual’s specifications. If it is out of range, replace the actuator.
4. Test the turbocharger bypass valve sensor. Disconnect its electrical connector and use a digital multimeter to check for voltage and ground at its terminals with the key on and engine off (KOEO). Compare your readings with your repair manual’s specifications. If they are not within range, check for continuity and resistance in the wiring and connectors of the sensor circuit. Repair any open or shorted wires as needed. If they are within range, reconnect the sensor and backprobe its signal wire with a digital multimeter while operating the actuator manually or with a scan tool command (if available). Observe if the signal voltage changes according to the position of the bypass valve. Compare your reading with your repair manual’s specifications. If it is out of range or does not change, replace the sensor.
5. Check the wiring and connectors in the bypass valve control circuit. Use a wiring diagram to identify the power, ground, and signal wires of the circuit. Use a digital multimeter to check for voltage drop, continuity, resistance, and shorts in the circuit. Repair any damaged wires or connectors as needed.
6. Check for other related codes. If there are other codes stored along with P0035, diagnose and fix them first before clearing the codes and testing the vehicle.

Conclusion

P0035 is a code that indicates a problem with the circuit that controls the turbocharger bypass valve. This code can cause various issues with your vehicle’s performance and emissions. If you notice any of the symptoms mentioned above, it is advisable to have your vehicle checked by a professional mechanic.

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