Is the bypass valve the same thing as the wastegate?

No, and confusing them sends the diagnosis in the wrong direction. The wastegate sits on the exhaust side and controls how much energy reaches the turbine, which is how boost level is regulated. The bypass valve sits on the intake side and does nothing to set boost level — its job is to release air that has already been compressed when the throttle closes. A wastegate fault changes how much boost you get. A bypass fault changes what happens to boost when you lift off.

The code says turbocharger but my car has a supercharger. Which is it?

The code covers both, and that is why the title names both. On a positive-displacement supercharged engine the bypass valve is a recirculation throttle that unloads the blower at light throttle so the engine is not burning fuel to make boost it will immediately throttle away. It is an efficiency device, so a fault costs fuel rather than power and there is no risk of the compressor surge that concerns a turbocharged engine. Identify which system you have before deciding how urgent the repair is.

Why does the car feel like the turbo has failed?

Because a bypass valve stuck or held open is a permanent leak between the pressurised side of the intake and the compressor inlet. The turbo spins up normally and makes pressure normally, and that pressure escapes back around it, so boost climbs and then falls away under load. The symptom is indistinguishable from a tired turbocharger from the driver's seat. It is worth ruling out this circuit before accepting a quote for the turbo, because the price difference is roughly ten to one.

Can I keep driving with it?

Usually yes in the short term, but the reason to fix it differs by engine. On a turbocharged car a valve that will not open means the compressor is stalling against a closed throttle every time you lift, which loads the thrust bearing in a direction it is not designed for, so the argument for fixing it promptly is bearing life rather than driveability. On a supercharged car the same fault only costs fuel. Either way the code is emissions-related on most platforms and will fail an inspection while it is stored.

OBD-II trouble code

P0033: Turbocharger/Supercharger Bypass Valve Control Circuit

The module found a fault in the circuit that operates the boost bypass valve. What the code costs you depends entirely on which kind of forced induction the car has — on a turbo it is a surge-protection device, on a supercharger it is a fuel-economy device, and the same code number means two different repairs.

Medium severityPowertrainFuel & AirDrivable short-term

Quick facts

System: Powertrain
Category: Fuel & Air
Severity: Medium severity
Drivable: Usually safe to drive short-term
Repair cost range: $40 – $600
DIY difficulty: Intermediate DIY

What does P0033 mean?

Every forced-induction engine needs a way to get rid of pressurised air it is no longer using. On a turbocharged engine that need arrives the instant you lift off the throttle: the compressor is still spinning at tens of thousands of rpm, the throttle plate has just slammed shut in front of it, and the air it is still pumping has nowhere to go. The bypass valve — also called a diverter or recirculation valve — opens at that moment and routes the trapped charge back to the compressor inlet. P0033 is the general, non-directional code for a fault in the circuit that operates that valve.

The first thing to establish is what the valve actually is on your engine, because two quite different designs share this code. The older and still common arrangement is a vacuum-actuated valve: a spring and diaphragm assembly plumbed to manifold vacuum, with a small electric solenoid elsewhere in the bay deciding when that vacuum reaches the diaphragm. The newer arrangement is a directly driven electric valve, a solenoid and pintle in one housing bolted to the compressor cover. On the vacuum design the control circuit belongs to the switching solenoid, not to the valve, so a circuit code names a part that may sit nowhere near the turbo and costs a fraction of what the valve does. Buying the wrong one is the standard way to spend money on this code twice.

The second thing to establish is what the valve is for on your engine, because that decides how urgent this is. On a turbocharged car the bypass valve exists to stop compressor surge — the aerodynamic stall that happens when a spinning compressor is asked to push against a closed throttle, which you hear as a chatter or flutter on lift and which loads the turbo's thrust bearing in a direction it is not built to take. On a supercharged car with a positive-displacement blower, the same code names something else entirely: a bypass throttle that recirculates air around the blower at light load so the engine is not spending fuel compressing air it will only throttle away again. That valve is an efficiency device. A supercharged engine with a stuck-shut bypass drives perfectly well and simply drinks more fuel; a turbocharged engine with a bypass that will not open is being mechanically punished every time you lift.

Because this is the general code rather than the low or the high one, it carries no statement about which direction the circuit failed in. Some manufacturers store it when the module saw an out-of-range condition that met neither directional threshold; others reserve it for faults it attributes to its own driver rather than to the load. In both cases the useful first measurement is at the connector with the engine running: command the valve with a scan tool and watch whether the control wire actually switches. That one test separates a module that is not driving the circuit from a circuit that is not responding, and it is worth doing before anything is unbolted.

What you will feel depends on the failure and the engine. A valve that no longer opens gives normal power and an audible chatter on gearshifts and throttle lift. A valve stuck open, or one whose solenoid has failed in the passing position, bleeds boost away continuously and feels exactly like a dying turbocharger — which is why this cheap code is worth ruling out before anyone quotes for an expensive one.

Common causes

Failed bypass or diverter valve solenoid
Failed vacuum switching solenoid on vacuum-actuated systems, with a healthy valve
Open, chafed, or heat-damaged wiring between the module and the valve
Corroded or unlatched connector at the valve or solenoid
Short to ground or to voltage on the control wire
Blown fuse on the circuit that feeds the valve
Poor ground or a degraded splice in the return path
Damage to the valve harness after intercooler, charge-pipe, or turbo work
Module driver failure, which is uncommon and should be the last conclusion rather than the first

Symptoms

Check engine light with normal power in many cases
Chatter or fluttering noise from the engine bay when lifting off the throttle
Boost that builds and then bleeds away, feeling like turbo failure
Hesitation or a flat spot between gearshifts
Reduced fuel economy on a supercharged engine with no change in how it drives
Engine entering a reduced-power or boost-limited mode on some platforms
Fault appearing shortly after intercooler, charge-pipe, or turbocharger work

Diagnostic steps

1.Identify the system first. Establish whether the engine is turbocharged or supercharged and whether the bypass valve is vacuum-actuated with a separate switching solenoid or a directly driven electric valve. This determines which part the circuit belongs to.
2.Look up how this manufacturer uses the general code. Some store it for an out-of-range condition that met neither directional threshold; others reserve it for faults on the module's own driver.
3.Command the valve with a scan tool while back-probing the control wire and watch whether it switches. This separates a module not driving the circuit from a circuit not responding.
4.Check the fuse feeding the valve before doing anything mechanical.
5.Measure the solenoid coil resistance against the manufacturer's figure for that exact part, and compare it to the reading with the connector attached to spot a wiring fault masquerading as a coil fault.
6.Confirm power and ground at the connector with the ignition on, then repeat as a loaded voltage-drop test with the valve commanded, since resistance invisible at rest appears once current flows.
7.Inspect the harness where it passes near the turbocharger, exhaust manifold, or charge pipe for heat damage and chafe.
8.On a vacuum-actuated system, confirm vacuum actually reaches the diaphragm when the solenoid is commanded, using a gauge rather than a finger.
9.Note whether the valve is stuck open or stuck shut, because the two failures present completely differently and only one of them affects power.

Repair cost

$40 – $600

A vacuum hose or a fuse is a few dollars. A vacuum switching solenoid is typically $60 to $180 fitted and is often the correct part on the older design even though the code names the bypass valve. A directly driven electric bypass valve runs $120 to $420 fitted depending on access, and the labour figure varies far more than the part does — some sit on the front of the compressor cover and take twenty minutes, others need the intake or charge piping off first. Wiring and connector repair is $70 to $250. The number worth keeping in mind is the one this code can save you: a bleeding bypass valve feels like turbocharger failure, and a turbocharger is a four-figure repair.

Estimate your repair

Run the numbers for your vehicle

Open the Repair Cost Estimator with turbocharger bypass / diverter valve replacement preselected. Adjust labor rate and vehicle category to fit your situation.

Estimate your repair cost

DIY vs shop

This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.