C0047 — Brake Booster Pressure Sensor (Subfault)

OBD2 code C0047 flags a problem with the turbocharger / supercharger boost control (C0047 — brake booster pressure sensor (subfault): causes, symptoms & fix). Short, gentle driving to a shop is usually possible. Common culprits: stuck wastegate or faulty boost control solenoid, clogged intake or exhaust (DPF/cat), faulty boost pressure sensor.

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Is it safe to drive?

Drive with caution Drive gently and avoid boost. The car will likely be down on power and may be in limp mode; ignoring boost faults can overheat the engine and destroy the turbo — a far more expensive repair.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm C0047 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many C0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the turbocharger / supercharger boost control for damage, corrosion, chafing or poor contact.
Subsystem check Pressure-test the intake piping for boost leaks — cracked intercooler hoses are the most common cause.
Subsystem check Command the boost control solenoid with a scanner and verify wastegate movement.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm C0047 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for C0047 (parts and labor, USD, independent shop rates): Replace boost control solenoid or actuator: $200–$600; Turbocharger replacement: $1,200–$3,500; Repair boost leak (hoses, clamps, intercooler): $100–$400. Overall, fixing C0047 usually costs between $100 and $3,500. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

Will C0047 clear itself?

Sometimes C0047 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

What is the most common cause of C0047?

The most common causes are: stuck wastegate or faulty boost control solenoid, clogged intake or exhaust (DPF/cat), faulty boost pressure sensor.

What does OBD2 code C0047 mean?

Is it safe to drive with C0047?

Drive gently and avoid boost. The car will likely be down on power and may be in limp mode; ignoring boost faults can overheat the engine and destroy the turbo — a far more expensive repair.

How do I diagnose C0047 myself?

Start with a scan: confirm C0047, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the turbocharger / supercharger boost control, and verify the suspect component against live data before buying parts.

C0047 — C0047 — Brake Booster Pressure Sensor (Subfault): Causes, Symptoms & Fix

When your OBD2 scanner pulls code C0047, it means the engine control module has detected a problem with the brake booster pressure sensor circuit. C0047 specifically indicates a subfault condition — the sensor itself may be functioning, but the signal it sends falls outside the acceptable range the ECU expects. The brake booster depends on proper vacuum pressure to assist braking effort, and when that sensor reports bad data, the system can't maintain correct assist levels.

The ECU continuously monitors this sensor while the engine runs, comparing its readings against stored parameters. If the pressure sensor output strays outside normal bounds for too long, C0047 gets set and the check engine light illuminates. The vehicle will often retain the freeze frame data associated with C0047, which captures engine speed, load, temperature, and vehicle speed at the exact moment the fault appeared — valuable information for pinpointing the trigger.

Brake booster pressure sensor failures rarely happen in isolation. More often, C0047 points to underlying issues elsewhere in the boost or vacuum system. The fault could stem from a failing sensor, a leak in the booster or its plumbing, electrical problems, or even mechanical wear in related components.

Symptoms of C0047

The most noticeable sign is a illuminated check engine light. Beyond that, you may experience reduced brake assist — the pedal will feel harder than usual, requiring more leg pressure to slow the car. Some drivers report a hissing sound from the brake booster area when pressing the pedal. In moderate cases, the ABS or stability control systems may behave oddly since they share data with the brake system. Severe failures can trigger limp-home mode, limiting speed and engine output. In rare instances, the engine may stall when coming to a stop because the ECU misinterprets the faulty sensor data.

Common Causes of C0047

The most frequent culprit behind C0047 is a worn or failing brake booster pressure sensor itself — these units can degrade over time from heat cycles and vibration. Vacuum leaks around the brake booster or its connecting hoses rank second; a torn diaphragm or cracked line breaks the pressure circuit. Wiring issues come next — corroded connectors, damaged harness insulation, or loose terminals near the firewall all disrupt the sensor signal. Less commonly, the fault traces to a failing vacuum pump or accumulator that supports the brake booster. Finally, in some vehicles, software glitches in the ABS module or body control computer can cause intermittent C0047 codes even with good hardware.

How to Diagnose C0047

Start by connecting a quality OBD2 scanner to confirm C0047 is active and not just a pending code from an old glitch. Record all freeze frame data before clearing anything — this snapshot tells you exactly what conditions existed when the fault occurred. Next, search for any technical service bulletins for your specific make, model, and year; manufacturers occasionally issue updates that resolve sensor-related codes without parts replacement.

Visually inspect the wiring harness running to the brake booster area, paying special attention to where it passes through the firewall. Look for cracked insulation, green corrosion at connectors, or wires pulled loose. With the engine off, check all vacuum lines feeding the booster for cracks, disconnections, or soft spots that collapse under pressure.

Use a hand-held vacuum pump to manually test the brake booster diaphragm — it should hold vacuum without bleeding down over 30 seconds. If it doesn't, the booster itself is faulty. For sensor-specific testing, consult your service manual for the acceptable voltage range at the sensor connector with the key on and engine off. Finally, clear the code and drive the vehicle through conditions similar to the freeze frame data. If C0047 returns, you've narrowed the problem to whatever component operates during that scenario.

Repair Options and Costs

Sensor replacement is usually the first repair to attempt — a genuine OEM or high-quality aftermarket brake booster pressure sensor runs $80–$200 for the part alone. Labor to replace it typically adds $60–$120 at an independent shop. If the brake booster itself has failed, a new or remanufactured unit costs $250–$600 depending on your vehicle, with $150–$300 in labor for installation. Vacuum line repairs are usually inexpensive — hose sections cost under $20, though diagnosing the exact leak location may run $100–$150 in labor. Wiring repairs, if the harness is damaged, can range from a simple terminal cleaning at no cost up to $300 or more if extensive harness work or replacement is needed.

How Much Does Fixing C0047 Cost?

The total repair bill for C0047 varies widely depending on what actually failed. Sensor replacement alone — the most straightforward fix — typically costs $140–$320 when combining parts and labor. If the brake booster requires replacement, expect to pay $400–$900 total. Vacuum line repairs stay on the lower end at $100–$200. Most vehicles fall somewhere in the $200–$500 range for an accurate diagnosis followed by the appropriate repair. Skipping professional diagnosis and guessing at parts can easily double your spending if you replace components unnecessarily.

Can You Drive with C0047?

Proceed with caution. The brake booster relies on engine vacuum to multiply your pedal force — without proper sensor feedback, brake feel becomes much harder and stopping distances may increase noticeably. While the vehicle remains technically drivable, you should limit driving to essential trips and apply extra pedal pressure when slowing. Get the code diagnosed within a week or two; continued driving with an actively failing booster puts extra strain on the entire braking system and can mask other developing problems.