P0047 is a diagnostic trouble code that points to a problem in the turbocharger or supercharger boost control circuit, specifically a low voltage condition. If your check engine light came on and you noticed a big loss of power, this code may be stored in your ECU. The good news is that you can usually track it down with basic tools and some patience. In this guide, you’ll learn what P0047 means, common causes, symptoms, how to diagnose it, and what repairs typically cost.
What Does P0047 Mean?
P0047 stands for “Turbocharger/Supercharger Boost Control ‘A’ Circuit Low.” In plain language, your engine computer (ECU) is seeing lower than expected voltage in the electrical circuit that controls boost pressure. This circuit usually includes a boost control solenoid, wiring, and sometimes an integrated pressure/position sensor.
When the ECU detects this low signal, it assumes the turbo or supercharger can’t be controlled correctly. To protect the engine, it often cuts power and may put the vehicle into a limp or reduced-power mode until the issue is resolved.
Quick Reference
- Code: P0047
- Meaning: Turbo/Supercharger boost control “A” circuit low
- Common Symptoms: Low power, limp mode, check engine light
- Typical Causes: Bad boost control solenoid, wiring fault, poor ground, sensor issues
- Severity: Moderate to high – can limit drivability and harm engine if ignored
Real-World Example / Field Notes
In the shop, I see P0047 most often on turbo diesel trucks and turbocharged gas engines that tow or are driven hard. A common scenario: a customer comes in complaining that their truck suddenly lost power on the highway, can’t get up to speed, and the check engine light is on. Scan shows P0047, sometimes along with underboost codes. Many times, the fix ends up being a failed boost control solenoid or a corroded connector down near the turbo where heat and moisture live. Once the circuit voltage is restored, power comes right back.
Symptoms of P0047
- Low power / poor acceleration – The vehicle feels sluggish, especially when climbing hills or passing.
- Limp mode – The ECU may limit boost and fuel, making the vehicle feel “stuck” at low power.
- Check engine light (MIL) – The warning light will usually be on solid, and P0047 is stored in memory.
- Reduced fuel economy – You may notice higher fuel consumption due to inefficient boost control.
- Turbo not spooling properly – You may hear less turbo whistle or feel delayed boost response.
- Black smoke on diesels – Some diesel engines may produce excess black smoke during acceleration.
- Harsh or frequent transmission shifts – On some vehicles, reduced power can cause odd shift behavior.
Common Causes of P0047
Most Common Causes
- Failed boost control solenoid (wastegate or VGT solenoid) – The solenoid that regulates turbo boost can short internally, stick, or fail electrically, causing a low voltage signal.
- Damaged wiring or connectors – Chafed wires, melted insulation near the turbo, or corroded connectors can drop voltage in the control circuit.
- Poor ground or power supply – Weak grounds, loose battery connections, or blown fuses feeding the solenoid circuit can trigger P0047.
- Short to ground in the circuit – A wire rubbing on metal can create a direct path to ground, pulling voltage low.
- Contaminated or stuck wastegate/VGT actuator – While more mechanical, a stuck actuator can overload the solenoid or cause abnormal readings.
Less Common Causes
- Faulty boost pressure sensor – Some systems integrate the control and sensing; a bad sensor can confuse the ECU and appear as a low circuit condition.
- ECU (PCM) internal fault – Rare, but a damaged driver circuit in the ECU can cause low voltage output to the solenoid.
- Aftermarket tuning or modifications – Aggressive tunes, deleted emissions equipment, or non-OEM turbos can upset the control strategy and trigger codes.
- Water intrusion – Deep water crossings or pressure washing the engine bay can get into connectors and cause intermittent low voltage.
- Previous repair errors – Misrouted wiring, wrong solenoid part number, or poor splices from earlier repairs can show up as P0047 later.
Diagnosis: Step-by-Step Guide
You’ll want a basic scan tool (preferably with live data), a digital multimeter, and access to a wiring diagram for your specific vehicle. A handheld vacuum pump or a bidirectional scan tool that can command the turbo actuator is a bonus. Always work with the engine cool when you’re near the turbo area.
- Confirm the code and record data – Use an OBD-II scanner to confirm P0047 and note any companion codes (like underboost or sensor codes). Save freeze frame data to see when it set.
- Perform a visual inspection – Check the harness and connectors going to the turbo boost control solenoid and actuator. Look for melted wires, broken clips, oil saturation, or green corrosion.
- Check fuses and power supply – Using the wiring diagram, locate the fuse and relay that feed the boost control circuit. Verify they’re intact and that you have battery voltage with the key on.
- Test the solenoid resistance – Unplug the boost control solenoid and measure resistance across its terminals with a multimeter. Compare to spec. An open or very low resistance usually means a bad solenoid.
- Verify voltage at the connector – With the key on, back-probe the solenoid connector. You should see a proper supply voltage and a control signal from the ECU (often a pulsed ground). If voltage is low or missing, move upstream in the circuit.
- Check for shorts to ground – With the solenoid disconnected, test the control wire for continuity to ground. A direct short will pull voltage low and set P0047.
- Inspect grounds and battery connections – Clean and tighten engine grounds and battery terminals. High resistance in these spots can cause low circuit voltage under load.
- Command the solenoid with a scan tool – If you have a bidirectional scanner, command the turbo actuator or boost solenoid on and off while watching live data and listening/feeling for it to click or move.
- Check turbo mechanical operation – Manually move the wastegate arm or VGT linkage (engine off, cool) if accessible. It should move smoothly without binding.
- Evaluate ECU only after all else checks out – If wiring, power, grounds, and the solenoid all test good, an internal ECU driver fault becomes more likely and should be confirmed by a professional.
Pro tip: Use Mode $06 data (if your scan tool supports it) to look at turbo/boost-related test results. It can show marginal components before they fully fail, especially on vehicles that only intermittently set P0047.
Possible Fixes & Repair Costs
Repairs for P0047 range from simple wiring fixes to component replacement. Common repairs include replacing the boost control solenoid, repairing or replacing damaged wiring/connectors, cleaning and freeing a sticky wastegate or VGT actuator, replacing a faulty boost pressure sensor, or in rare cases, repairing or replacing the ECU. Typical costs at a shop can range from about $100–$250 for basic wiring or connector repairs, $200–$450 for a new solenoid or sensor installed, and $700+ if an ECU or complex turbo actuator is involved. Labor rates, vehicle make, and parts availability all affect the final bill.
Can I Still Drive With P0047?
In many cases you can still drive with P0047, but you probably won’t enjoy it. The vehicle may have severely reduced power, making highway merging, towing, or steep hills difficult and potentially unsafe. On some models, the ECU will limit boost and fuel to protect the engine, so you’ll be stuck in limp mode. Short trips to get home or to a repair shop are usually okay, but you should avoid heavy loads, aggressive driving, and long-distance travel until the issue is fixed.
What Happens If You Ignore P0047?
If you ignore P0047, you risk long-term engine and turbo damage. Running with improper boost control can lead to excessive exhaust temperatures, carbon buildup, poor fuel economy, and in extreme cases, turbo or engine failure. It can also mask new problems because the check engine light is already on, making future diagnosis harder and more expensive.
Related Codes
- P0027 – Exhaust Valve Control Solenoid Circuit Range/Performance Bank 1
- P0026 – Intake Valve Control Solenoid Circuit Range/Performance Bank 1
- P0019 – Crankshaft Position Camshaft Position Correlation Bank 2 Sensor B
- P0018 – Crankshaft Position Camshaft Position Correlation Bank 2 Sensor A
- P0017 – Crankshaft Position Camshaft Position Correlation Bank 1 Sensor B
- P0016 – Crankshaft Position Camshaft Position Correlation Bank 1 Sensor A
- P0009 – Engine Position System Performance Bank 2
- P0008 – Engine Position System Performance Bank 1
- P0007 – Fuel Shutoff Valve “A” Control Circuit High
- P0006 – Fuel Shutoff Valve “A” Control Circuit Low
Key Takeaways
- P0047 means the turbo/supercharger boost control “A” circuit is reading low voltage to the ECU.
- You’ll usually notice low power, possible limp mode, and a check engine light.
- Most common causes are a bad boost control solenoid or wiring/connector problems near the turbo.
- Diagnosis involves checking power, ground, circuit continuity, and solenoid operation with a scan tool and multimeter.
- Repairs typically range from a simple wiring fix to solenoid replacement, with costs varying by vehicle and labor rates.
- Driving for a short time is possible, but ignoring the code can lead to costly turbo or engine damage.
Vehicles Commonly Affected by P0047
P0047 is especially common on turbocharged diesel trucks and SUVs, such as Ford Power Stroke, Ram/Cummins, and GM Duramax platforms. You’ll also see it on many turbocharged gas engines from manufacturers like Ford (EcoBoost), Volkswagen/Audi (TSI/TFSI), Subaru, Hyundai/Kia, and some Nissan and Mercedes-Benz diesel models. Any vehicle with a turbo or supercharger that uses an electronically controlled wastegate or variable geometry turbo can potentially set this code when the boost control circuit has issues.
FAQ
Can I clear P0047 and keep driving if the vehicle feels okay?
You can clear the code, but if the underlying problem isn’t fixed, P0047 will almost always return. The system is monitored continuously, and the ECU will set the code again as soon as it sees the low circuit voltage condition. It’s better to diagnose and repair the cause rather than repeatedly clearing it.
Is P0047 always caused by a bad turbo?
No, P0047 is usually an electrical or control issue, not a failed turbocharger itself. Most of the time the culprit is the boost control solenoid, wiring, or connectors. The turbo may still be mechanically fine. Only after the circuit checks out should you suspect internal turbo problems.
How serious is P0047 for my engine?
P0047 is serious enough that you shouldn’t ignore it. While it may not cause instant engine failure, poor boost control can lead to high exhaust temperatures, extra soot, and long-term wear. It also affects drivability and fuel economy. Plan to diagnose and repair it as soon as you reasonably can.
Can a weak battery or charging system cause P0047?
Yes, in some cases a weak battery, failing alternator, or poor grounds can cause low voltage in multiple circuits, including the boost control circuit. If you have other electrical issues (dim lights, slow cranking), it’s smart to test the battery and charging system while diagnosing P0047.
Do I need a dealer to fix P0047, or can an independent shop handle it?
Most independent shops with good diagnostic equipment can handle P0047 without any problem. The key is having proper wiring diagrams, a decent scan tool, and experience with turbocharged systems. A dealer may be helpful for complex ECU or actuator programming, but for common solenoid and wiring issues, a qualified independent mechanic is usually just as effective and sometimes more affordable.