OBD-II trouble code
P0249: Turbocharger/Supercharger Wastegate Solenoid "B" Low
The second wastegate solenoid circuit is reading low — the module expected voltage on it and found none. A short to ground and an open circuit both look identical from the module's side, which keeps the test list short and specific.
Quick facts
- System
- Powertrain
- Category
- Fuel & Air
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $110 – $1,000
- DIY difficulty
- Intermediate DIY
What does P0249 mean?
P0249 is the circuit-low member of the wastegate solenoid "B" family. The module monitors its own output circuit, and this code sets when it finds no voltage present on that circuit at a time when voltage should be there — in other words, the solenoid is de-energized when the strategy called for it to be energized, or the circuit simply cannot hold the voltage the module put on it.
Two different faults produce that same observation, and recognizing that is what makes this diagnosis efficient. A short to ground pulls the circuit down: the voltage the module supplies drains away and the monitor reads low. An open circuit — a broken wire, a disconnected connector, a failed solenoid coil, a blown fuse — means the module never sees its voltage return through the load at all, and it reads that as low too. So the suspect list is short and there is no point being clever about it: fuse, connector, coil resistance, short to ground, end-to-end continuity. Work through those five in order and the fault will surface.
The second solenoid gives you an advantage most single-solenoid diagnoses lack. If the "A" solenoid is healthy, you have a known-good component on the same engine to compare against. Measure the "A" solenoid's coil resistance and you have the real specification for your engine, not a value from a chart that may not apply. Inspect the "A" connector and you know what a good pin fit and a clean terminal look like. If the "B" solenoid reads open or wildly different, that comparison is all the confirmation you need.
And if both P0249 and its "A" counterpart P0245 are stored together, the reading changes completely. Two solenoid coils do not usually fail on the same morning. What they share does fail — a fuse, a relay, an ignition-switched power feed, a ground point. Check the shared elements first, because one repair clears both codes.
One physical point specific to this circuit matters more than it does on most: the harness run. The "B" solenoid is typically the one associated with the second turbocharger, which on a transverse V6 is usually the rear turbo and on a longitudinal V8 the far bank. That means the harness often runs longer, sits closer to the exhaust manifold and turbine housing, and passes more heat sources than the "A" circuit does. Chafed insulation and heat-hardened, cracked wire jackets are more likely here than they would be on a circuit in a cooler part of the engine bay. When you follow the harness, look specifically for shiny or flattened spots where it has rubbed a bracket edge, and for sections that have gone stiff and dark from radiant heat.
The driver-side consequence is consistent. The module cannot control boost through a circuit that will not hold voltage, and it will not run a turbocharged engine on unreliable boost control, so it defaults to the safe state — wastegate open, minimal boost, reduced power. The car drives, but it drives as though the turbo is not there. On a twin-turbo engine that may present as a distinct imbalance rather than an overall flatness. This is protection, not a mechanical failure, and normal power returns as soon as the circuit is repaired. Notably, it also means the sluggishness tells you nothing about the condition of the turbocharger itself.
Common causes
- Failed "B" wastegate solenoid with an open or shorted coil
- Blown fuse feeding the boost control solenoid circuit
- Open or broken wire between the module and the "B" solenoid
- Control wire shorted to ground
- Corroded, loose, or water-intruded connector at the "B" solenoid
- Chafed insulation where the harness rubs a bracket edge or bulkhead
- Heat-hardened and cracked wire jacket where the harness passes the second turbo or exhaust manifold
- Backed-out, spread, or pushed-in terminals in the solenoid connector
- Failed relay or shared power feed — normally sets the "A" code alongside this one
- Poor ground in the solenoid control circuit
- PCM solenoid driver fault, rare and diagnosed only after everything else checks out
Symptoms
- Check engine light with P0249 stored
- Noticeable loss of power — the engine feels like the turbo is not contributing
- Reduced-power or limp mode
- Uneven boost between the two turbochargers or banks in live data
- Poor acceleration and slow throttle response
- Hesitation or a rough handover on sequential-turbo systems
- Reduced fuel economy
- Boost target and actual boost diverging in live data
- Black smoke on some diesel applications
Diagnostic steps
- 1.Record all stored codes. If P0245 (the "A" solenoid low code) is also stored, check what the two circuits share — a fuse, a relay, a power feed, a ground — before condemning either solenoid.
- 2.Identify which physical solenoid your engine calls "B" from service data, and confirm the engine actually has a second boost control solenoid.
- 3.Check the fuse feeding the boost control solenoid circuit first. It is the cheapest possible outcome and takes a minute.
- 4.Inspect the "B" solenoid connector for corrosion, water intrusion, green deposits, and backed-out or spread terminals.
- 5.Measure the "B" solenoid's coil resistance with the key off. An open reading or a value far from specification condemns it.
- 6.Measure the healthy "A" solenoid's coil resistance for comparison. That gives you the real specification for your engine rather than a generic figure.
- 7.Confirm the solenoid has power on its feed side with the key on.
- 8.With the connector disconnected at both ends, check the control wire for a short to ground.
- 9.Check end-to-end continuity on the control wire between the module connector and the solenoid connector to rule out an open.
- 10.Follow the harness run visually, looking for shiny or flattened spots where it has rubbed a bracket, and for stiff, dark, heat-hardened sections near the second turbo and exhaust manifold.
- 11.Command the solenoid on and off with a scan tool and listen or feel for the click. Silence with good power and a good command signal means the solenoid has failed internally.
- 12.Wiggle-test the harness while watching for the code to reset or for live data to drop out, since chafed wiring often faults intermittently.
- 13.Suspect the module driver only after the fuse, connector, coil, wiring, and ground have all been verified good.
Repair cost
$110 – $1,000
A blown fuse is a few dollars. The solenoid runs $50-$220 in parts, and labor on the "B" position tends to be higher than on "A" because the second solenoid is often the buried one — 0.3-2 hours, putting a straightforward solenoid replacement between $110 and $500. Connector and terminal repairs are commonly $120-$300. Repairing a chafed or heat-damaged harness section generally runs $180-$500, because the cost is in tracing the fault rather than in the wire itself, and heat-damaged sections near a turbo often need to be replaced rather than spliced. Diagnosis commonly runs $110-$200. The upper end reflects harness work behind or under intake plumbing on engines where reaching the second turbo means removing components to get at it.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with wastegate actuator replacement preselected. Adjust labor rate and vehicle category to fit your situation.
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.