P0035
UniversalTurbo/Super Charger Bypass Valve Control Circuit High
Medium SeverityThis code indicates an electrical problem in the control circuit of the turbo/supercharger bypass valve. This malfunction can prevent the valve from operating correctly, leading to improper boost pressure regulation and noticeable performance issues.
⚠️ Before You Begin (Safety First)
Always practice safety first when working on your vehicle. Ensure the engine is cool before touching components. Disconnect the battery before performing any electrical work. Be mindful of hot engine parts and rotating components.
Common Symptoms
- Check Engine Light illuminated
- Reduced engine power or sluggish acceleration
- Turbocharger/supercharger not boosting correctly
- Hesitation or rough idling
- Possible audible turbo/supercharger noises (e.g., louder whine, fluttering)
Common Causes
- Faulty turbo/supercharger bypass valve
- Open or short circuit in the bypass valve control wiring
- Poor electrical connection at the bypass valve connector
- Faulty Engine Control Module (ECM) or Powertrain Control Module (PCM)
Frequently reported on: Subaru WRX (2008-2014), Ford F-150 EcoBoost (2011-2016), Volkswagen GTI (2006-2013), BMW 335i (2007-2010), Chevrolet Cruze (2011-2015)
Diagnostic Steps
- Visually inspect the wiring harness and connector leading to the turbo/supercharger bypass valve for any signs of damage, corrosion, or loose connections.
- Using a multimeter, check for proper voltage and ground at the bypass valve connector according to your vehicle's service manual specifications.
- Test the bypass valve for proper operation. Some valves can be tested by applying power and ground to see if they actuate, or by checking their internal resistance.
- If wiring and valve appear fine, clear the code and test drive the vehicle to see if the P0035 returns.
- If the issue persists, consider consulting a professional as a faulty ECM/PCM or a more complex electrical issue might be present.
👨🔧 When to Call a Professional
If you've checked the wiring and the bypass valve and the code persists, or if you lack experience with electrical diagnostics, it's best to consult a professional mechanic. A complex electrical fault or an issue with the Engine Control Module (ECM) may require specialized tools and expertise.
Commonly Asked Questions
What specifically does 'control circuit high' mean for P0035?
A 'control circuit high' typically means the ECM/PCM is detecting a voltage in the control circuit that is higher than the expected range, often indicating an open circuit, a short to voltage, or a problem with the valve itself that is causing abnormal resistance.
Can I drive my car with a P0035 code?
While you might be able to drive the car, it's not recommended for prolonged periods. The vehicle will likely be in 'limp mode' or experience reduced power, and improper boost control can potentially lead to further engine damage over time if not addressed.
Is it possible for a vacuum leak to cause a P0035 code?
While a vacuum leak can affect boost pressure, P0035 specifically points to an electrical fault within the control circuit of the bypass valve, not necessarily a mechanical issue like a vacuum leak. However, a significant vacuum leak could indirectly affect how the ECM interprets boost and valve operation.
How can I test the bypass valve itself?
You can often test the bypass valve by checking its resistance with a multimeter across its terminals. Compare the reading to your vehicle's service manual specifications. For solenoid-type valves, you might also apply 12V and ground to see if it actuates (clicks or moves) while listening or observing its plunger.
Will replacing the bypass valve always fix P0035?
Not always. While a faulty bypass valve is a common cause, the code specifically points to the 'control circuit.' Therefore, wiring issues, connector problems, or even a rare ECM/PCM fault could also be the root cause. Proper diagnosis of the circuit is crucial before replacing parts.