P0034

Turbocharger/Supercharger Bypass Valve A Control Circuit Low

Q: Is it safe to drive with P0034?

Short trips are usually fine, but expect reduced power. Prolonged driving under boost with a stuck valve can stress the turbo, so get it checked soon.

Q: Can I just clear P0034?

It will come back until the circuit fault is repaired — this is an electrical control code, not a passing glitch.

Turbo / boost control Generic OBD-II High

What it means

P0034 sets when the ECM sees low voltage (usually a short-to-ground or open) in the control circuit for the turbo or supercharger bypass valve. That valve manages boost pressure, so the fault typically shows up as weak boost, sluggish acceleration, and sometimes a reduced-power limp mode. It's an electrical circuit problem, not a mechanical no-start issue.

High

Can I keep driving? Usually drivable, but the engine may drop into reduced-power limp mode and boost will be down until it's fixed.

Real-world scan data

Seen in

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

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 and weak acceleration
Turbo/supercharger not building normal boost
Possible reduced-power (limp) mode
Slightly worse fuel economy

Common causes

Most likely first

Faulty turbo/supercharger bypass (diverter) valve solenoidLikely
Short-to-ground or open in the control-circuit wiringCommon
Corroded or loose connector at the valveCommon
Low or missing supply voltage to the circuitLess often
Failed ECM/PCM driver (least likely)Less often

How to diagnose & fix

Work through it in order

Read freeze-frame data, then inspect the bypass-valve connector and wiring for damage, chafing, or corrosion.
Check for a short-to-ground and confirm the solenoid has power and ground with the key on.
Measure the solenoid's resistance against spec; replace the bypass valve if it's out of range.
Repair any wiring/connector faults, clear the code, and road-test to confirm boost returns.
If wiring and valve check out, suspect the ECM driver circuit.

FAQ

Quick answers

Is it safe to drive with P0034?+

Short trips are usually fine, but expect reduced power. Prolonged driving under boost with a stuck valve can stress the turbo, so get it checked soon.

Can I just clear P0034?+

It will come back until the circuit fault is repaired — this is an electrical control code, not a passing glitch.

Read & clear P0034 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX