When you see a P0047 code pop up, your vehicle’s computer-what we call the PCM-is telling you there’s a low voltage or weak signal in the turbocharger or supercharger boost control circuit, specifically in the so-called “A” circuit. I’ve run into this code on quite a few different makes: Hyundai, Toyota, Ford Powerstroke, Chevy Duramax, VW, Kia-you name it, if it’s got a turbo or supercharger, this code can rear its head. The boost control system’s job is to manage how much extra air gets crammed into your engine, giving you that satisfying surge of power when you step on it. Most modern setups use a variable geometry turbo (VGT), where adjustable vanes control boost at different engine speeds. The PCM controls those vanes using an electronic solenoid or actuator, and a position sensor keeps tabs on things. If you’re working with an older or more basic turbo or supercharger, you’ll likely have a wastegate or bypass valve handling the job. When the PCM senses a low signal from the boost control solenoid, up comes the P0047 code. In short, your system can’t regulate boost properly, and that spells trouble for your engine’s performance.
DTC P0047
4918
7 minutes of readingCauses and P0047 Trouble Code
From my time under the hood and thumbing through countless service manuals, here are the most common reasons you’ll see a P0047 code show up:
- Faulty boost pressure or turbo position sensor - these guys are notorious for failing or getting gummed up, sending bogus info to the PCM.
- A worn-out turbocharger or supercharger - mechanical issues inside the unit itself can throw this code.
- Defective boost control solenoid - this is the electronic valve that actually manages boost, and in my experience, it’s often the weak link.
- Wiring issues - corroded, broken, or loose wires and connectors in the boost control circuit can cause all sorts of headaches.
- A PCM problem - rare, but I’ve seen it once or twice.
- Vacuum leaks (for systems that use vacuum to move the valve) - even a tiny split in a hose can mess up the works.
If you ask me, the most frequent offenders are the solenoid or the wiring. But don’t stop there-always check the whole system to get to the root of the problem.
Symptoms Associated with the P0047 Code
When P0047 is active, it’s usually pretty obvious something’s up. The check engine light comes on-and that’s your first warning. You’ll probably notice your car feels gutless, especially when you try to accelerate. That’s your turbo or supercharger not giving you the boost you expect. Sometimes, the engine just feels lazy or slow to pick up. Once in a while, you might pick up some odd noises from the turbo area, but honestly, it’s usually the lack of power and that ever-present warning light that tip you off.
Diagnosis of the P0047 Engine Code
Here’s how I go after a P0047 code-it’s a method that’s saved me plenty of time and headaches:
- Start with a visual inspection. Open the hood and eyeball all the wiring and connectors around the turbo or supercharger, the boost control solenoid, and any sensors. Look for loose plugs, damaged wires, or corrosion. If your system uses vacuum lines, squeeze those hoses and listen for leaks-a cracked line can be sneaky.
- Don’t skip checking for technical service bulletins (TSBs) specific to your vehicle. I’ve found more than one weird issue solved by a factory update.
- If everything looks fine, pull out your scan tool. Command the boost control solenoid on and off, and watch both sensor readings and engine RPM. If RPM jumps but the sensor stays flat, I start thinking about a bad sensor or its wiring. If nothing changes, focus on the solenoid, turbo, or the wiring itself.
- Next up, put a multimeter on the solenoid’s connector. Check for power and ground while you’re triggering the solenoid with the scan tool. Missing power or ground? Time to chase the wiring.
- If the solenoid’s getting juice, check its resistance with an ohmmeter (grab the specs from the manual). If it’s out of whack, replace it. Sometimes, I’ll bench test the solenoid-hook it up to power and ground to see if it clicks or moves.
- While you’re in there, inspect the turbo or supercharger for obvious damage or debris-just pull off the intake duct. If you spot mangled vanes or blades, you’ve found a problem.
- Finally, check the boost pressure or position sensor for the right voltage and signal. Most have three wires: power, ground, and signal. If any are missing, trace the circuit all the way back to the PCM.
Here’s a pro-tip from the garage: It’s a lot easier-and safer-if you have a second set of hands when you’re running the scan tool and poking around under the hood.
Common Mistakes When Fixing OBD2 Code P0047
A classic mistake I see is folks immediately swapping out the turbo or the solenoid before checking the wiring or connectors. That’s a quick way to burn cash without solving the real issue. Another one? Ignoring tiny vacuum leaks on systems that use vacuum lines-just a small crack can throw the whole system off. And don’t forget: skipping over TSBs might mean missing a simple factory fix. Always tackle the basics first before you reach for the pricey parts.
How Serious Is the OBD Code P0047
If you’re tempted to ignore this code, let me stop you right there. Sure, your car might still get you from A to B, but you’re flirting with disaster if you keep driving around with a boost control issue. Without proper boost, your engine’s going to run rough-and if the turbo lets go mechanically, shrapnel can get sucked right in. That’s game over for your engine. You might also see clouds of exhaust smoke, terrible fuel mileage, and possibly damage to the catalytic converter or DPF. Problems can snowball fast, so don’t push your luck-get it checked and fixed as soon as possible.
How to Repair DTC P0047
Here’s how I tackle a P0047 code, based on what’s worked over the years and what’s in the official guides:
- Repair or replace any damaged wiring or connectors in the boost control circuit-don’t underestimate how often this is the problem.
- Swap out the boost control solenoid if it fails your resistance or function checks.
- Patch up any vacuum leaks by replacing brittle or cracked hoses.
- If the boost pressure or position sensor isn’t sending a proper signal, replace it.
- If you find damage inside the turbo or supercharger, you’ll need to rebuild or replace it-there’s no shortcut here.
- And in those rare cases where the PCM is at fault, reprogramming or replacing it is your last resort.
Once you’re done, always clear the code and take it for a test drive. That’s the only way to know for sure you’ve nailed the fix.
Conclusion
So, what’s the bottom line? If you’re seeing P0047, your turbo or supercharger boost control system isn’t doing its job-and that’s bad news for both performance and engine life. Take it from someone who’s fixed more of these than I can count: start simple with wiring and vacuum checks, then move on to the solenoid and sensors. Don’t brush this code aside. The risk just isn’t worth it. Your best bet is to follow a clear, step-by-step diagnostic routine, fix what you find, and confirm the repair with a solid test drive. That’s how you keep your engine happy-and your ride running strong.
