What does the P0035 code mean?
The P0035 fault code, applicable to all car manufacturers, means “Turbocharger/Supercharger Bypass Valve A Control Circuit High“.
Background Information: This code indicates that the Engine Control Module (ECM) has detected an abnormally high voltage signal in the control circuit for the Bypass Valve A, which regulates boost pressure in turbocharged or supercharged engines. The bypass valve diverts excess exhaust gases around the turbine when the system would otherwise exceed safe limits, preventing over-boost and potential engine damage. When the ECM reads a “circuit high” condition, it assumes the valve is stuck open or the sensor is shorted, prompting protective measures like reduced power or limp-mode activation.
Symptoms of Error Code P0035
Signs of error P0035 may include:
- The Check Engine Light (CEL) or Malfunction Indicator Lamp (MIL) is illuminated on the dashboard, sometimes flashing before staying solid.
- Reduced engine power or noticeable loss of power during acceleration, making the vehicle feel “flat” or sluggish.
- Poor engine performance or lack of turbocharger boost, with a drop in the characteristic turbo whine under hard acceleration.
- Increased fuel consumption (reduced MPG) as the engine may run inefficiently.
- Rough idle or stalling of the engine due to unstable air-fuel mixture.
- Possible black smoke or unusual exhaust emissions from the tailpipe, indicating incomplete combustion.
- Squealing or clanking sounds from the turbocharger or turbo pipes due to excessive or insufficient boost pressure.
- Limp-mode activation, where the dashboard may display a “Reduced Power” or “Engine Protection” warning, limiting engine RPMs to protect the drivetrain.
- Over-boosting or under-boosting conditions, which may cause damage to engine components if left unaddressed.
Main Causes of Error Code P0035
- A faulty or stuck turbocharger/supercharger bypass valve actuator – the internal solenoid or piston may be stuck open.
- Damaged, frayed, shorted, or corroded wiring and connectors in the bypass valve control circuit harness.
- A short circuit to battery voltage in the control circuit, forcing the ECM to interpret the signal as “circuit high”.
- A faulty Engine Control Module (ECM) or Powertrain Control Module (PCM) with an internal driver circuit failure.
- Poor electrical connection or corrosion at the bypass valve connector or ECM connector.
- Vacuum leaks in the system that can affect the performance of the bypass valve.
- Sensor issues related to the turbocharger/supercharger monitoring system.
- Improper calibration or programming of the ECM, especially after turbocharger upgrades or hardware replacements.
- Moisture intrusion or contamination in the valve’s connector from steam, coolant leaks, or road-salt spray.
How to Diagnose Error Code P0035?
- Connect a professional obd2 scanner or obd2 diagnostic tool to retrieve and confirm the P0035 code. Note any additional codes (e.g., P0034, P0093) and freeze frame data.
- Perform a thorough visual inspection of the bypass valve wiring harness and connectors near the turbocharger outlet. Look for cracked insulation, melted sections, loose terminals, or corrosion.
- Check the relevant fuse for the bypass valve control circuit in the vehicle’s fuse box.
- With the ignition ON and engine OFF, measure the voltage at the valve’s control wire relative to chassis ground using a digital multimeter. A reading near battery voltage (≈12V) indicates a high circuit condition.
- Test the bypass valve actuator operation by applying the specified voltage directly to the valve (bypassing the ECM). If the valve doesn’t open and close smoothly, it may be faulty.
- Measure the resistance of the bypass valve solenoid using a multimeter. Compare the reading to manufacturer specifications (commonly between 10-30 ohms at 20°C/68°F).
- Check for continuity and shorts in the wiring between the valve connector and the ECM connector using a wiring diagram.
- If all wiring and the valve check out, the issue may be a faulty ECM driver circuit, requiring professional diagnosis with advanced obd2 diagnostic scanner capabilities.
Possible Causes and Diagnostic Methods
| Possible Cause | How to Check? |
| Faulty Bypass Valve Actuator | Measure resistance of the solenoid (typically 10-30Ω). Apply voltage directly to test mechanical operation. |
| Short circuit to voltage in wiring | Test for voltage on the control circuit with the connector disconnected and ignition ON. |
| Open circuit or high resistance | Perform continuity test on the circuit wires from the valve to the ECM. |
| Poor connection/corrosion | Inspect the valve and ECM connectors for green/white corrosion, bent pins, or looseness. |
| Faulty ECM/PCM output driver | Using a scan tool, check if the ECM provides proper PWM signal to the heater circuit. |
| Vacuum leak affecting valve operation | Visually and audibly inspect vacuum lines and connections near the turbo system. |
Tools needed: OBD2 diagnostic scanner or capable obd reader, digital multimeter, basic hand tools (sockets, wrenches), safety glasses, wiring diagram for your specific vehicle, electrical contact cleaner.
How do I fix error code P0035? (Solutions to the Problem)
Simple Fixes
- Repair damaged wiring or replace corroded connectors in the bypass valve control circuit. Use solder and heat shrink for permanent wire repairs.
- Clean corroded connector pins with electrical contact cleaner and reseat connections securely.
- Replace a blown fuse for the bypass valve control circuit if found.
- Clear the code with your obd tool scanner after making repairs and perform a test drive to see if it returns.
In-depth Diagnosis and Repair Solutions
- Replace the faulty turbocharger/supercharger bypass valve assembly. Always use a part that meets OEM specifications.
- If the ECM’s driver circuit is faulty, the Engine Control Module may need to be repaired or replaced and reprogrammed with a VIN-matched unit.
- Repair any vacuum leaks found in the system, as they can affect bypass valve performance.
- Update or recalibrate the ECM software if service bulletins address bypass valve control parameters.
Troubleshooting Based on Symptoms
| Symptom | Possible Solution |
| Check Engine Light is on with code P0035. | Focus diagnosis on the bypass valve ‘A’ control circuit: wiring, connector, then the valve itself. |
| Code returns immediately after clearing. | Indicates a persistent hard fault. Likely a failed valve, severe wiring short to voltage, or faulty ECM. |
| Loss of boost and reduced power. | The bypass valve may be stuck open. Test valve operation and replace if necessary. |
| Intermittent boost loss or rough idle. | Often caused by an intermittent wiring issue or poor connection. Check harness for chafing. |
| Abnormal sounds from turbo system. | Inspect bypass valve and associated piping for leaks or mechanical damage. |
Common Error Code P0035 in Vehicles
Toyota/Lexus P0035: Found in turbocharged models like the Toyota Supra (with BMW B58 engine), Lexus IS 200t/300, NX 200t, and RC 200t/300. Toyota’s definition is “Turbocharger Bypass Valve Control Circuit High”. Diagnosis involves checking the valve’s resistance and the wiring from the ECM. The bypass valve is typically located near the turbocharger outlet. Using a professional-grade obd2 diagnostic scanner is recommended for Toyota/Lexus to access specific parameters and perform actuator tests.
Honda/Acura P0035: Appears in turbocharged Honda Civic (1.5L VTEC Turbo), Accord (1.5T/2.0T), CR-V (1.5T), and Acura RDX, TLX, MDX with turbo engines. Check the wiring harness near the turbo for heat damage. A common issue is the connector becoming brittle from sustained high temperatures. Also inspect the vacuum lines connected to the bypass valve diaphragm.
Ford P0035: Common in EcoBoost models like F-150 (2.7L/3.5L EcoBoost), Escape (1.5L/2.0L EcoBoost), Focus ST/RS, Fusion (1.5L/2.0L EcoBoost), and Explorer ST. Ford’s PCM monitors the bypass valve circuit voltage closely. Wiring chafing where the harness passes near sharp edges or hot exhaust components is a frequent cause. A thorough visual inspection along the entire harness route is crucial.
Chevrolet/GMC P0035: Found in turbocharged models like Chevrolet Silverado with 2.7L Turbo, Equinox 1.5T, Malibu 1.5T, and GMC Terrain 1.5T. GM vehicles are sensitive to aftermarket exhaust work that may damage sensor wiring. Diagnose by checking circuit resistance and voltage at the valve connector. Refer to specific service manuals for wiring diagrams and resistance specifications.
Nissan/Infiniti P0035: Seen in turbocharged Altima (VC-Turbo), Rogue (1.5T), Sentra (1.6T), and Infiniti Q50/Q60 (3.0T VR30). Nissan may define it as “Turbocharger Bypass Valve Control Circuit High”. The valve connector, often located in the engine bay near the turbo, is susceptible to heat degradation and corrosion.
Hyundai/Kia P0035: Common in turbo models like Elantra N-Line/Sport (1.6T), Sonata (1.6T/2.5T), Santa Fe (2.5T), Sorento (2.5T), and Sportage (1.6T). Issues often stem from a failed valve actuator or wiring problems. A capable obd2 diagnostic tool can monitor boost pressure and valve command in real-time to aid diagnosis.
BMW P0035: Occurs in numerous turbocharged BMW models (designated with “i” or “d” for diesel). BMW’s definition is “Charge pressure control, bypass valve: Control circuit”. Diagnosis typically requires advanced diagnostic software (like ISTA) to perform guided tests and read live data from the DME (ECU). The electronic wastegate actuator is often integrated into the turbo assembly.
Mercedes-Benz P0035: In turbocharged Mercedes models (petrol and diesel). Requires the STAR Diagnostic system for accurate fault reading and component activation tests. Can be linked to faults in the turbocharger actuator or its control wiring from the Engine Control Unit (ECU). The bypass valve is often part of a more complex turbocharger control system.
Subaru P0035: In turbocharged Subaru models like WRX, STI, Forester XT, and Legacy GT. Subaru’s system monitors the boost control solenoid circuit. Check for wiring issues along the firewall and near the turbo. Also inspect the vacuum lines connected to the wastegate actuator and bypass valve.
Volkswagen/Audi P0035: Affects numerous VAG turbo models (TSI and TFSI engines). VW/Audi vehicles often require a diagnostic tool like VCDS or OBDeleven for in-depth scans of the Engine Control Module. Faults can be in the turbocharger bypass regulator valve (N249) or its wiring to the ECU. Common in Golf GTI, Audi A4, etc.
Chrysler/Dodge/Jeep/Ram P0035: Found in turbocharged models like Dodge Charger/Challenger (2.0L Turbo), Jeep Cherokee (2.0L Turbo), and Ram 1500 with 3.0L EcoDiesel. A common cause is a poor connection at the PCM itself or wiring issues. A proper obd2 diagnostic scanner is needed to clear the code after repair and perform boost pressure tests.
Mitsubishi P0035: In turbocharged models like Lancer Evolution, Outlander (2.4L MIVEC Turbo). Referencing service manuals, the probable causes are a failed turbocharger wastegate solenoid, an open/short in its circuit, or a failed engine-ECU. The solenoid resistance should be checked against specifications.
Mazda P0035: Common in turbocharged Mazda models like Mazda3 2.5 Turbo, Mazda6 2.5T, CX-5/CX-9 2.5T. Diagnosis follows similar steps: visual inspection, fuse check, resistance measurement of the turbo bypass solenoid, and wiring continuity tests back to the PCM.
Land Rover/Range Rover P0035: In turbocharged and supercharged models like Range Rover Sport, Evoque, Discovery. Land Rover’s definition aligns with “Turbocharger or Supercharger Bypass Valve Control Circuit High”. Professional diagnosis with Land Rover’s specific diagnostic equipment (SDD/Pathfinder) is often required due to complex boost control systems.
Volvo P0035: In turbocharged Volvo models (Drive-E engines). Volvo’s system uses an electronically controlled wastegate actuator. Diagnosis requires VIDA (Volvo’s diagnostic software) to properly test the turbocharger control module and actuator functionality.
P0035 Frequently Asked Questions
What is the first thing I should do when I see code P0035?
The first step is to use a reliable obd2 scanner to confirm the code and check for any other related codes (like P0034 or P0093). Do not ignore it, as it affects engine performance and can lead to serious damage if over-boost occurs. Record the freeze frame data if your scanner supports it, as it can provide clues about when the fault occurs (engine load, RPM, temperature).
Is it safe to drive my car with the P0035 code?
You can usually drive, but with significant limitations. The vehicle will likely be in a reduced power or limp mode to protect the engine from potential over-boost. Extended driving is not recommended as it can strain the engine and turbo system. The check engine light indicates an active fault in the boost control system that requires attention.
How much does it typically cost to repair a P0035 error?
Costs vary widely. A simple wiring repair might cost $150-$300. Replacing the turbocharger bypass valve/solenoid typically ranges from $200 to $600 for parts and labor, depending on accessibility. If the turbocharger wastegate actuator is integrated and faulty, replacement can cost $800-$2,000+. ECM replacement and programming can exceed $1,000. Always get a proper diagnosis first.
Can I replace the bypass valve myself to fix P0035?
Yes, if you have intermediate mechanical skills and proper tools. You will need an obd reader to confirm the code, basic socket/wrench sets, and possibly turbo-specific tools. The valve is usually located near the turbocharger, which can be challenging to access. Always disconnect the battery and allow the turbo to cool completely before working. Follow manufacturer torque specifications for connections.
Why did P0035 appear after my car battery died or was disconnected?
When the ECM loses power, it resets and performs comprehensive self-tests upon restart. During these tests, if it detects a momentary anomaly or resistance value out of specification in the bypass valve circuit, it may store P0035. Using your obd tool scanner to clear the code once may resolve it if it was a transient glitch, but if it returns, a physical fault exists.
What’s the difference between P0035 and P0034 or P0033 codes?
All three codes relate to the turbocharger bypass valve control circuit. P0033 indicates a general circuit malfunction. P0034 specifically means the circuit voltage is detected as Low. P0035 means the circuit voltage is detected as High. The diagnostic approach differs based on whether the circuit is reading high or low voltage.
Will disconnecting the battery clear the P0035 code?
It may temporarily turn off the Check Engine Light, but the code is stored as a Diagnostic Trouble Code (DTC) in the ECM’s non-volatile memory. To properly clear the code and turn off the light, you need to use an OBD2 scanner after the underlying issue has been fixed. Some vehicles may also clear codes after a certain number of successful drive cycles without the fault recurring.
Can a problem with the turbocharger itself cause code P0035?
Yes, indirectly. If the turbocharger wastegate is stuck closed or the variable geometry mechanism is faulty, it can cause over-boost conditions that the ECM tries to compensate for by commanding the bypass valve. This can stress the control circuit. However, P0035 is primarily an electrical circuit fault code. Mechanical turbo issues might set different codes like P0299 (underboost) or P0234 (overboost).
My car passed inspection with the Check Engine light on for P0035. Is that okay?
In most U.S. states and regions with emissions testing, an illuminated Check Engine Light is an automatic failure. The vehicle should not pass a safety or emissions inspection with an active P0035 code, as it indicates a fault in the emissions control and boost management system.
After fixing the issue, do I need a special tool to reset the Check Engine light?
You will need an OBD2 scanner, obd reader, or obd2 diagnostic tool that can clear codes. Most basic code readers have this function. After repairs, clear the code, drive the vehicle through a complete drive cycle (which varies by manufacturer), and ensure the light does not return. Some vehicles may require multiple drive cycles to reset readiness monitors.
Could a blown fuse cause the P0035 code?
Typically, no. A blown fuse would usually cause an open circuit or no power condition, which might set a low voltage code like P0034. P0035 indicates excessive voltage in the circuit, which is more likely caused by a short to battery voltage, a faulty ECM driver, or a stuck valve presenting incorrect resistance.
How critical is it to use OEM (Original Equipment Manufacturer) parts for repair?
For turbocharger control components like bypass valves and actuators, using OEM or high-quality OEM-equivalent parts is highly recommended. These components operate under high temperatures and pressures, and precise calibration is crucial for proper boost control. Cheap aftermarket parts may have different response characteristics, leading to driveability issues or triggering other codes.
What does “Bypass Valve A” mean in the code definition?
“Bypass Valve A” typically refers to the primary bypass valve in the turbocharger system. Some vehicles may have multiple bypass valves or control circuits for different operating conditions (e.g., high boost vs. low boost). The “A” designation helps distinguish between them when multiple similar components exist in the system.
Can I clean a turbo bypass valve to fix P0035?
Sometimes. If the valve is mechanically stuck due to carbon buildup, careful cleaning with appropriate solvents might free it. However, if the internal solenoid or electrical components are faulty, cleaning won’t help. Always test the valve’s electrical resistance and mechanical operation before attempting cleaning. Use caution as these components are often expensive and delicate.
Will P0035 affect my vehicle’s fuel economy?
Yes, significantly. When the bypass valve circuit is faulty, the ECM cannot properly regulate boost pressure. This often causes the engine to run rich (excess fuel) or lean (insufficient fuel), both of which reduce fuel efficiency. You may notice a drop of 3-8 MPG or more until the issue is resolved.
P0035 Related OBD2 Errors
- P0033 – Turbocharger/Supercharger Bypass Valve “A” Control Circuit
- P0034 – Turbocharger/Supercharger Bypass Valve “A” Control Circuit Low
- P0036 – Turbocharger/Supercharger Bypass Valve “B” Control Circuit
- P0037 – Turbocharger/Supercharger Bypass Valve “B” Control Circuit High
- P0038 – Turbocharger/Supercharger Bypass Valve “B” Control Circuit Low
- P0299 – Turbocharger/Supercharger Underboost Condition
- P0234 – Turbocharger/Supercharger Overboost Condition
- P2263 – Turbocharger/Supercharger Boost System Performance
- P2563 – Turbocharger Boost Control Position Sensor Circuit
Important Note! While a P0035 code may not immediately prevent your vehicle from running, ignoring it can lead to serious engine damage from over-boost conditions, reduced fuel efficiency, and potential failure of the turbocharger or catalytic converter. Always address boost control system faults promptly. When working on turbo systems, allow components to cool completely and follow all safety procedures. The use of a professional-grade obd2 diagnostic scanner is recommended for accurate diagnosis and verification of repairs.