How is P0248 different from P0249 and P0250?

P0249 and P0250 are electrical codes about the circuit reading low or high, and they are diagnosed with a meter. P0248 says the circuit is being commanded and responding but the boost result is wrong for the conditions — the solenoid is not controlling wastegate activity the way the calibration intended. That moves the diagnosis out of the harness and into the mechanical chain: the vacuum lines, the actuator diaphragm, the actuator spring, whether the wastegate flapper moves freely, and whether there is a boost leak on that side. Probing wires on P0248 is usually time spent confirming something the code already told you works.

How do I tell which turbo is the problem?

Live data, before any disassembly. On a twin-turbo engine, watch commanded wastegate duty cycle and actual boost for both sides simultaneously under load. If one side is making noticeably more or less boost than the other at the same command, you have localized the fault to a bank without touching a bolt. On a sequential system the more useful window is the handover point between the small and large turbos, since that is where a mis-controlled second solenoid shows up as hesitation, a flat spot, or a surge rather than as a uniform power loss.

Should I replace the solenoid for P0248?

Not as the first move, which is the opposite of the advice for P0249 and P0250. The word solenoid in the title pulls people toward that part, but P0248 specifically describes a case where the solenoid is responding. Check the free things first: move the wastegate linkage by hand with the engine cold, hand-pump the actuator and see whether it holds vacuum and travels fully, and inspect the vacuum lines. If all of that is good, then pull the solenoid and inspect it for carbon and oil fouling — a partially clogged solenoid does fit this code, and that is the point at which replacing it makes sense.

Is it safe to drive with P0248?

Gently and for short distances, usually. Most platforms cap boost or enter a reduced-power mode, which is the module protecting the engine rather than a mechanical failure, and the car remains stable to drive to a shop. What argues against leaving it is the failure direction you cannot see from the driver's seat. If the wastegate is stuck closed rather than open, boost creep and overboost are possible, and sustained overboost damages pistons, head gaskets, and turbochargers. Elevated temperatures, abnormal smoke, or rattling from the turbo are all reasons to stop driving it and get it looked at.

OBD-II trouble code

P0248: Turbocharger/Supercharger Wastegate Solenoid "B" Range/Performance

The second wastegate solenoid is being commanded and responding, but the boost result is outside what the module expects. On a twin-turbo engine this often shows up as one side pulling harder than the other, which live data will reveal long before a parts swap will.

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: $130 – $1,800
DIY difficulty: Intermediate DIY

What does P0248 mean?

P0248 is the performance member of the wastegate solenoid "B" family, and it makes a fundamentally different claim from its siblings. P0249 and P0250 are electrical codes — the circuit is reading low or high. P0248 says the signal from the solenoid circuit is outside the expected voltage window for the conditions, or that the solenoid is not controlling wastegate activity in the intended manner, depending on how the manufacturer applies it. Either way the message is the same: the control loop is closed, the solenoid is responding, and the outcome is still wrong.

That means the diagnosis lives in the mechanical chain, not in the harness. The module commands a duty cycle. The solenoid meters vacuum or pressure. The actuator diaphragm moves against a spring. The linkage pushes the wastegate flapper. The flapper diverts exhaust past the turbine. Every one of those links can fail while the electrical circuit tests perfect. A solenoid partially fouled with carbon or oil passes flow but not the right amount. A cracked or heat-hardened vacuum line bleeds the signal away. A leaking actuator diaphragm moves lazily or stops short of full travel. A weakened spring changes where the wastegate sits under load. And a flapper bound by carbon and thermal deposits will not move at all, which on several turbo platforms is a documented and common failure.

What makes P0248 more tractable than the equivalent "A" code is that a second solenoid almost always means a second turbocharger, and a second turbocharger means you have a comparison. On a twin-turbo engine, watch commanded duty cycle and actual boost for both sides side by side under load. If one turbo is making noticeably more boost than the other at the same command, you have localized the problem to a bank without removing a single part. On a sequential system, the revealing moment is the handover — a solenoid that is not controlling correctly usually shows up as hesitation, a flat spot, or a surge at the point where the small turbo hands off to the large one, rather than as a uniform loss of power.

The direction of failure tells you what to expect. A wastegate that will not close produces underboost on that side: flat power, boost that never reaches target, and on a twin-turbo engine an audible and measurable imbalance. A wastegate that will not open produces boost creep and eventually overboost on that side, which is the more damaging direction and frequently drags P0234 along with it. Both conditions set P0248, because both are boost failing to track the command.

Before anything is ordered, do the free mechanical check. With the engine cold and completely off, move the second turbocharger's wastegate linkage by hand. Full free travel with light spring resistance is normal. Notchiness, sticking, or a hard stop short of full travel explains this code entirely — and tells you that a new solenoid, which is what most people buy first on a code with the word solenoid in the title, would have changed nothing.

One honest caveat on modified vehicles: if the turbochargers, actuators, boost controller, or calibration have been changed, P0248 can be the module correctly reporting that command and result no longer line up, with every component physically healthy. On a modified engine, establish what was changed and when the code first appeared before replacing parts.

Common causes

Wastegate flapper or linkage binding on the second turbocharger from carbon and thermal cycling
Leaking wastegate actuator diaphragm on the second turbo
Cracked, split, heat-hardened, or disconnected vacuum or pressure lines in the "B" control path
Partially clogged or carbon-fouled "B" solenoid passing some flow but not the commanded amount
Weak or fatigued wastegate actuator spring on the second turbo
Weak or lost vacuum supply to the "B" solenoid
Boost leak on the second turbo's charge piping, so the module never sees the boost it commanded
Failing second turbocharger unable to reach its commanded boost
Exhaust leak upstream of the second turbine reducing available exhaust energy
Sequential-system handover valve or actuator not moving correctly
Sticking or seized electric wastegate actuator on platforms that use one
Aftermarket turbo, actuator, boost controller, or tune changing what the wastegate strategy expects

Symptoms

Check engine light with P0248 stored
Underboost and flat power, or boost creep in the opposite failure direction
Uneven boost between the two turbochargers or banks in live data
Hesitation, a flat spot, or a surge at the turbo handover on sequential systems
Reduced-power or limp mode
Commanded wastegate duty cycle and actual boost diverging in live data
Rattling, whining, or hissing from the second turbo or its plumbing
Abnormal exhaust smoke, including black smoke on diesel applications
Reduced fuel economy
Spark plug fouling on gasoline applications running mismanaged boost
Elevated engine or transmission temperatures under sustained load

Diagnostic steps

1.Record all stored codes. If P0247, P0249, or P0250 is also present, the circuit is faulted as well — repair the electrical fault first, then re-check whether P0248 still sets.
2.Identify which physical solenoid and which turbocharger your engine calls "B" from service data before ordering anything.
3.Watch commanded duty cycle and actual boost for both turbochargers side by side in live data under load. An imbalance between the two localizes the fault to one bank without disassembly.
4.On sequential systems, pay particular attention to the handover point, since that is where a poorly controlled second solenoid shows up most clearly.
5.With the engine cold and off, move the second wastegate's linkage by hand through its full range. Binding or a hard stop short of full travel explains this code by itself.
6.Apply vacuum to the second turbo's wastegate actuator with a hand pump, confirm it holds, and watch the rod travel its full expected distance.
7.Inspect every vacuum and pressure line in the "B" control path for cracks, hardening, splits at the barbs, oil saturation, and incorrect routing.
8.Verify vacuum supply at the "B" solenoid, and on diesel applications confirm the vacuum pump produces full vacuum.
9.Remove the "B" solenoid and check it for carbon and oil fouling. Command it with a scan tool and confirm it flows and blocks cleanly rather than passing partial flow in both states.
10.Compare the "B" solenoid against the "A" solenoid for resistance and commanded behaviour, since the healthy one is a known-good reference on the same engine.
11.Pressure-test the charge air system on the second turbo's side for leaks at clamps, couplers, intercooler end tanks, and piping seams.
12.Listen for an exhaust leak upstream of the second turbine, and check the air filter and intake ducting for restriction.
13.Inspect the second turbocharger for shaft play, wheel damage, and oil contamination only after everything upstream has checked out.
14.On modified vehicles, establish whether the turbos, actuators, boost controller, or calibration have been changed before condemning any component.

Repair cost

$130 – $1,800

This is a mechanical-chain code, so the honest range is wide. A cracked vacuum line is often under $120. A wastegate solenoid runs $50-$220 in parts, but the "B" position is frequently the buried one, so labor of 0.3-2 hours puts a genuine solenoid replacement between $130 and $500. A wastegate actuator replacement on the second turbo typically lands between $350 and $1,100 depending on access — often higher than the same job on the "A" side for exactly the same reason. Freeing or servicing a carbon-bound wastegate can run $400-$1,000 because of the disassembly, and on some engines the wastegate is not serviceable separately from the turbine housing. Diagnosis commonly runs $130-$250 since this code requires live-data comparison of both turbos under load. The top of the range reflects wastegate assembly or turbine housing work; a full turbocharger replacement is a separate and larger expense.

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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.