Which solenoid is wastegate solenoid "B"?

It depends entirely on the engine, and this is worth settling before any parts are ordered. On a twin-turbo engine, "B" is usually the solenoid for the second turbocharger or the second bank. On a sequential system it typically manages the handover from the small turbo to the large one. Some diesel applications split the job differently again, with separate solenoids for wastegate or variable-geometry control and for a related boost-management valve. Only the service data for your specific engine will tell you which valve is "B" — and since the "B" solenoid is frequently the harder one to reach, knowing which it is also tells you what the labor is really going to cost.

P0247 and P0243 are both stored. Did two solenoids fail?

Almost certainly not. Two solenoids failing on the same day is a coincidence worth being suspicious of. What is far more likely is that something they share has failed — a common fuse, a relay, an ignition-switched power feed, or a shared ground. Check what feeds both circuits before you condemn either solenoid, because one repair there clears both codes. As a general rule on this family: one code means one component, two codes mean something common to both.

Does P0247 mean I need a new turbocharger?

Very rarely. P0247 is about the second solenoid's control circuit, not about the turbocharger. The great majority of these diagnoses come down to a failed solenoid, damaged wiring, a corroded connector, a blown fuse, or a cracked vacuum line — all inexpensive parts. The turbocharger is essentially never the cause of a solenoid circuit code. Work through the electrical and vacuum checks completely, and also move the second wastegate's linkage by hand while the engine is cold, because a bound wastegate will defeat a brand-new solenoid.

Can I test the "B" solenoid against the "A" solenoid?

Comparing them is one of the real advantages of a "B" code. Coil resistance, connector condition, expected voltages, and how the solenoid behaves during a scan tool output test can all be checked against a component you know is working on the same engine. Physically swapping the two is a different matter — only do that if you have confirmed they carry the same part number, because some platforms use different valves in the two positions, and fitting the wrong one creates a second problem to chase alongside the first.

OBD-II trouble code

P0247: Turbocharger/Supercharger Wastegate Solenoid "B"

A general fault in the second wastegate control solenoid circuit. Because a second solenoid only exists on twin-turbo, sequential-turbo, and some diesel applications, the first job is establishing which physical valve your engine calls "B" — and whether it has one at all.

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: $120 – $1,400
DIY difficulty: Intermediate DIY

What does P0247 mean?

P0247 is the parent code of the wastegate solenoid "B" family, exactly as P0243 is the parent of the "A" family. P0249 is the same circuit reading low, P0250 is it reading high, and P0248 is the range and performance member where the solenoid responds but boost does not follow. P0247 reports a fault without classifying its direction, so if any of the other three is stored alongside it, use that one — it narrows the search considerably.

The word carrying all the weight in this code is "B". A second wastegate control solenoid is not standard equipment. It exists only where the engine actually needs one, and identifying which arrangement your engine uses is the entire first step of the diagnosis. Twin-turbo engines commonly fit one solenoid per turbocharger, or one per bank, so the module can control each side's boost independently. Sequential systems use a second solenoid to manage the transition from the small turbo that spools early to the large one that carries higher load. And a number of diesel applications separate the functions differently again, with one solenoid handling wastegate or variable-geometry control and a second handling a related boost-management valve. What "B" means physically is a manufacturer decision, and only the service data for your specific engine will tell you which valve it is.

This matters commercially as well as diagnostically. On a twin-turbo engine, the "B" solenoid is frequently the harder one to reach — the rear turbo on a transverse V6, the far bank on a longitudinal V8, the one buried under intake plumbing. Two solenoids that cost the same in parts can differ by two hours in labor, and knowing which one you are dealing with before the car goes on a lift changes the estimate.

When both P0247 and its "A" counterpart P0243 are stored together, resist the reading that two solenoids failed on the same day. Look at what they share instead. Two solenoids fed from the same fuse, the same relay, the same ignition-switched power feed, or grounded to the same point will code together the moment that shared element fails — and one repair clears both. A single failed solenoid sets one code. A shared power or ground problem sets two.

When only P0247 is stored, the healthy "A" solenoid becomes a genuinely useful known-good reference. You can compare coil resistance, connector condition, commanded behaviour on a scan tool, and expected voltage values against a component you know is working on the same engine. That is a diagnostic advantage single-solenoid systems do not have. What it does not license is physically swapping the two solenoids to test — only do that after confirming they carry the same part number, since some platforms use different valves for the two positions.

The usual symptom is loss of power. With a boost control circuit faulted, the module will not attempt to coordinate a multi-turbo system on incomplete control authority, so it defaults to a safe state — wastegate open, minimal boost, reduced power. On sequential systems the more distinctive complaint is a rough or hesitant handover between turbos rather than a flat loss of power throughout the range. Either way the car drives; it just drives as though the turbos are not contributing. That is protection rather than mechanical failure, and normal power returns once boost control is restored.

Common causes

Failed second wastegate control solenoid — the most common single cause
Corroded, loose, or water-intruded connector at the "B" solenoid
Open, shorted, or chafed wiring in the "B" solenoid control circuit
Blown fuse or failed relay feeding the boost control solenoids — normally sets both "A" and "B" codes together
Shared power feed or ground failure affecting both solenoids
Cracked, disconnected, or heat-hardened vacuum lines on vacuum-operated systems
Leaking wastegate actuator diaphragm on the second turbocharger
Weak or lost vacuum supply to the solenoid
Wastegate flapper or linkage binding on the second turbocharger from carbon and thermal cycling
Heat damage to the harness where it runs near the second turbo or exhaust manifold
Poor ground at the solenoid or in its control circuit
PCM solenoid driver fault, rare and diagnosed only after everything else checks out

Symptoms

Check engine light with P0247 stored
Noticeable loss of power — the engine feels like the turbos are not contributing
Reduced-power or limp mode
Rough, hesitant, or delayed handover between turbos on sequential systems
Uneven boost between the two turbochargers or banks in live data
Poor acceleration and slow throttle response
Reduced fuel economy
Whistling or airflow noise if a vacuum line has come off
Black smoke on some diesel applications

Diagnostic steps

1.Record all stored codes. P0248, P0249, or P0250 alongside P0247 classifies the fault — range and performance, circuit low, or circuit high — and narrows the search immediately.
2.Note whether the "A" solenoid codes P0243, P0245, or P0246 are also stored. Both sides coding together points at a shared fuse, relay, power feed, or ground rather than at two failed solenoids.
3.Identify which physical solenoid your engine calls "B" from service data, and confirm the engine actually has a second boost control solenoid before ordering anything.
4.Check the fuse and relay feeding the boost control circuit. This is the cheapest possible outcome and the fastest to rule out.
5.Inspect the "B" solenoid connector for corrosion, water intrusion, and backed-out or spread pins.
6.Measure the solenoid's coil resistance with the key off and compare it against specification — and against the healthy "A" solenoid, which gives you a known-good value on the same engine.
7.Confirm the solenoid receives power and that the module is switching its control side, using a scan tool output test or a test light.
8.Command the "B" solenoid on and off with a scan tool and listen or feel for it clicking. A silent solenoid with good power and a good command signal has failed internally.
9.On vacuum systems, verify vacuum supply at the solenoid and inspect every hose in the path for cracks, hardening, and disconnection.
10.Check the second turbocharger's wastegate actuator diaphragm by applying vacuum with a hand pump and confirming it holds.
11.With the engine cold and off, move the second wastegate's linkage by hand. It should travel freely with light spring resistance.
12.Trace the harness run to the "B" solenoid looking for chafing and heat damage, since this circuit often passes closer to the exhaust than the "A" circuit does.
13.Suspect the module driver only after the fuse, relay, wiring, ground, solenoid, vacuum path, and wastegate have all been verified good.

Repair cost

$120 – $1,400

The solenoid itself is typically $50-$220 in parts, but labor on the "B" position is often higher than on "A" because the second solenoid is frequently the buried one — the rear turbo on a transverse engine, or the far bank on a longitudinal one. Expect 0.3-2 hours, putting the common repair between $120 and $500. A blown fuse or relay is under $80. Vacuum hose replacement is often under $120. Wiring and connector repairs generally land between $130 and $350, with heat-damaged harness sections at the higher end because the labor is in the tracing. Diagnosis commonly runs $110-$200 since identifying which solenoid is "B" takes more than a code read. The upper end covers a wastegate actuator replacement on the second turbo or freeing a mechanically bound wastegate; turbocharger replacement is a separate and much larger expense this code rarely justifies.

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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.