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P0035 Code Explained: Turbocharger Bypass Valve Control Circuit High Causes, Symptoms & Fixes

OBD-II scanner displaying P0035 beside a turbocharger with the electronic bypass valve, wiring harness and electrical connector highlighted near the compressor housing.

If your OBD-II scanner displays P0035, your vehicle’s Engine Control Module (ECM) or Powertrain Control Module (PCM) has detected that the turbocharger bypass valve control circuit voltage is higher than expected.

The generic SAE definition for P0035 is:

Turbocharger Bypass Valve Control Circuit High

Depending on the manufacturer, the affected component may also be called the:

Unlike P0033, which indicates a general control circuit malfunction, and P0034, which indicates a low-voltage condition, P0035 specifically means the ECM has detected excessive voltage or insufficient current flow in the bypass valve control circuit.

Common causes include:

Although the vehicle will usually continue driving normally, turbocharger performance, throttle response, and boost control may be affected. Compressor surge may also occur if the bypass valve cannot operate correctly.

Looking for additional OBD-II diagnostic information? Browse our growing library:

P0035 Quick Facts

ItemInformation
OBD-II CodeP0035
DescriptionTurbocharger Bypass Valve Control Circuit High
CategoryPowertrain
SystemTurbocharger Boost Control
SeverityModerate
Safe to Drive?Usually yes
Typical RepairsWiring repair, bypass valve replacement
Estimated Cost$75–$1,200+

What Does P0035 Mean?

P0035 means the ECM has detected that the turbocharger bypass valve control circuit voltage is higher than its calibrated operating range.

On most vehicles, a Circuit High fault indicates the ECM is not seeing the expected current draw from the bypass valve circuit.

Common reasons include:

Unlike boost pressure codes such as P0299 (Turbo Underboost) or P0234 (Engine Overboost), P0035 monitors the electrical circuit, not actual boost pressure.

What Does the Turbocharger Bypass Valve Do?

The turbocharger bypass valve protects the turbocharger whenever boost pressure is suddenly no longer needed.

When the driver quickly releases the accelerator:

  1. The throttle plate closes.
  2. Pressurized intake air has nowhere to go.
  3. The ECM commands the bypass valve open.
  4. Pressurized air is redirected back into the intake.
  5. Compressor surge is prevented.

Without a functioning bypass valve, compressed air can reverse through the compressor wheel, producing compressor surge and placing additional stress on the turbocharger.

Turbocharger Bypass Valve vs Blow-Off Valve

Although often confused, they are slightly different.

Factory Bypass Valve

Blow-Off Valve

Many manufacturers use the terms diverter valve, compressor bypass valve, and turbo bypass valve interchangeably.

How the Turbocharger Bypass System Works

Under acceleration:

During throttle lift:

Depending on the manufacturer, the valve may be:

How the ECM Detects P0035

The ECM continuously monitors:

The ECM may store P0035 when:

P0033 vs P0034 vs P0035

These three codes diagnose the same system but identify different electrical faults.

CodeDescription
P0033Turbocharger Bypass Valve Control Circuit
P0034Turbocharger Bypass Valve Control Circuit Low
P0035Turbocharger Bypass Valve Control Circuit High

Generally:

Symptoms of P0035

Common symptoms include:

Some vehicles may display only the Check Engine Light.

Common Causes of P0035

1. Open Bypass Valve Solenoid

The most common cause of P0035 is an internally open solenoid.

Possible causes include:

2. Broken Control Wire

The control wire may break because of:

3. Open Power Wire

Loss of power prevents the valve from operating.

Possible causes include:

4. Loose or Disconnected Connector

Inspect for:

5. Corroded Connector

Corrosion creates excessive resistance.

Inspect for:

6. High Circuit Resistance

Resistance may result from:

Voltage-drop testing is more effective than simple continuity testing.

7. Failed Turbo Bypass Valve

Mechanical failure may include:

Some electronically controlled valves contain integrated electronics.

8. Failed Vacuum Solenoid

Vacuum-operated systems use an electrically controlled vacuum solenoid.

Failure may trigger P0035.

9. Vacuum Hose Problems

Inspect for:

Although vacuum leaks usually create performance issues rather than electrical faults, they may accompany P0035.

10. Incorrect Replacement Valve

Incorrect aftermarket valves may have:

Always verify part numbers.

11. Aftermarket Blow-Off Valve Modifications

Some aftermarket kits:

These modifications frequently trigger P0035.

12. Damaged Wiring Harness

Inspect the complete harness for:

13. Failed Relay

Some manufacturers use a dedicated relay.

Internal relay failure may interrupt power.

14. ECM Driver Failure

Although uncommon, the ECM output transistor may fail.

Always verify:

before replacing the ECM.

Is P0035 Serious?

P0035 is generally considered moderately serious.

The vehicle normally remains driveable.

However, prolonged driving may lead to:

Can You Drive With P0035?

Usually yes.

Avoid aggressive driving if:

Repair should be scheduled as soon as practical.

How to Diagnose P0035

Step 1

Scan for additional trouble codes.

Related turbocharger codes include:

Step 2

Inspect the bypass valve connector.

Check for:

Step 3

Inspect the wiring harness.

Look for:

Pay particular attention to areas near:

Step 4

Measure bypass valve resistance.

Compare resistance with manufacturer specifications.

An open circuit indicates a failed solenoid.

Step 5

Verify power supply.

Measure battery voltage at the bypass valve connector.

Step 6

Test the control wire.

Check for:

Step 7

Perform voltage-drop testing.

Inspect:

Step 8

Command the bypass valve.

Using a bidirectional scan tool:

Step 9

Inspect vacuum-operated components.

Check:

Step 10

Inspect the turbocharger.

Look for:

Step 11

Check Technical Service Bulletins

Some manufacturers have released updated bypass valves, revised harnesses or software updates for recurring P0035 issues.

Step 12

Verify Repair

After repairs:

  1. Clear diagnostic trouble codes.
  2. Start the engine from cold.
  3. Road test under boost.
  4. Monitor desired versus actual boost.
  5. Confirm bypass valve operation.
  6. Verify P0035 does not return.

Common Repairs

RepairEstimated Cost
Wiring repair$100–400
Connector replacement$75–250
Vacuum hose replacement$20–150
Vacuum solenoid replacement$120–350
Turbo bypass valve replacement$180–500
Turbo actuator replacement$300–900
Turbocharger replacement$1,000–2,500
ECM replacement/programming$1,000–2,500

Common Diagnostic Mistakes

Vehicles Commonly Affected

P0035 is commonly found on turbocharged vehicles including:

How to Prevent P0035

To reduce the likelihood of P0035:

Frequently Asked Questions

What does P0035 mean?

P0035 indicates the ECM has detected a high-voltage condition in the turbocharger bypass valve control circuit.

What causes P0035?

The most common causes include:

Can a bad bypass valve cause P0035?

Yes. An internally open bypass valve solenoid is one of the most common causes.

Can wiring cause P0035?

Yes. Broken or open wiring frequently causes this code.

Can an aftermarket blow-off valve cause P0035?

Yes. Many aftermarket modifications eliminate or alter the factory electronic bypass valve and can trigger this code.

Can vacuum leaks cause P0035?

Vacuum leaks may contribute to bypass valve performance problems, although P0035 is primarily an electrical circuit fault.

Is P0035 serious?

It is generally considered moderately serious. While the vehicle is usually driveable, prolonged compressor surge or poor boost control can shorten turbocharger life.

Can I drive with P0035?

Usually yes, provided there are no severe boost issues or limp mode conditions.

Will clearing P0035 fix it?

No. The code will return if the underlying electrical fault remains.

Can P0035 damage the turbocharger?

If compressor surge occurs repeatedly because the bypass valve cannot operate, turbocharger damage may eventually result.

Final Thoughts

The P0035 code indicates the ECM has detected a high-voltage condition in the turbocharger bypass valve control circuit. In most cases, the problem is caused by an open solenoid, broken wiring, poor electrical connections, or excessive circuit resistance rather than a failed turbocharger.

Begin diagnosis by inspecting the connector and wiring around the turbocharger, as heat damage is common. Verify power and ground, measure bypass valve resistance, perform voltage-drop testing, and command the valve with a bidirectional scan tool before replacing expensive components.

Properly repairing P0035 restores turbocharger response, prevents compressor surge, improves drivability, and helps extend turbocharger life.

Related Articles

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