Turbocharger/Supercharger Bypass Valve A Control Circuit
What it means
P0033 means the ECM detected a fault in the control circuit for the turbo/supercharger bypass (diverter) valve "A". That valve vents excess boost, so a circuit fault leaves boost control unreliable — you may feel reduced or surging power. The usual causes are the control solenoid, its connector, or wiring. Despite some databases flagging this as a misfire code, it is a boost-control circuit fault.
Can I keep driving? Yes — you may notice reduced boost and power; drive gently until repaired to avoid over-working the turbo system.
Real-world scan data
Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.
Common symptoms
What you'll notice
- Check-engine light on
- Reduced power or acceleration
- Boost that surges or falls off
- Possible turbo flutter or unusual intake noise
Common causes
Most likely first
- Failed bypass (diverter) valve control solenoidLikely
- Open or short in the bypass valve control circuitCommon
- Loose or corroded connector at the solenoidCommon
- ECM control-circuit driver faultLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame data to confirm when the fault sets.
- Inspect the bypass valve solenoid connector and wiring for opens, shorts, or corrosion.
- Measure the solenoid resistance and command it with a scan tool to confirm it actuates.
- Check for correct power and ground at the solenoid connector.
- Replace the solenoid if faulty; consider the ECM only after wiring checks out.
FAQ
Quick answers
Is it safe to drive with P0033?+
Can I just clear P0033?+
Related codes
Read & clear P0033 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.