P047C — Exhaust Pressure Sensor “B” Circuit Low #

Note: The wording of this code may vary depending on the manufacturer.

• Ford: Exhaust Pressure Sensor “B” Circuit Low Input
• GM: Exhaust Pressure Sensor “B” Circuit Low Voltage
• Chrysler: Exhaust Back Pressure Sensor ‘B’ Electrical Circuit Low
• Volkswagen/Audi: Exhaust Pressure Sensor 2 – Signal too Low

Summary for code P047C #

When your vehicle displays code P047C, it means the engine control module (ECM) has detected a low voltage signal from the exhaust pressure sensor “B”. This sensor monitors exhaust gas pressure, typically before or after the diesel particulate filter (DPF) or turbocharger. The ECM uses this information to manage emissions and optimize turbocharger operation. If the signal drops below the expected range, the ECM triggers P047C to alert you to a potential issue. Left unaddressed, this problem can lead to increased emissions or even engine performance concerns.

Frequent symptoms for code P047C #

A P047C code doesn’t always announce itself with fireworks, but certain symptoms are common. While some drivers might notice little difference, others could experience noticeable changes in how the vehicle behaves. Watch for these signs:

• Illuminated check engine light (CEL)
• Reduced engine power or “limp mode”
• Increased exhaust smoke
• Poor acceleration, especially under load
• Unusual exhaust odor
• Possible DPF regeneration issues (on diesel vehicles)

Probable causes for code P047C #

Several culprits can trigger a low voltage reading from the exhaust pressure sensor “B”. Understanding the most common causes helps focus diagnosis and repair, saving time and money:

1. Faulty exhaust pressure sensor “B” (sensor itself is defective)
2. Damaged or corroded sensor wiring/connectors (open, short, or poor connection)
3. Obstructed or leaking sensor hose/pipe (carbon build-up or cracked lines)
4. Exhaust leaks upstream or around the sensor
5. ECM (engine control module) malfunction (rare)

Step-by-step diagnostics for code P047C #

Diagnosing P047C is like following a detective’s trail—methodical steps prevent overlooking a simple fix. Here’s a proven process:

• 1. Verify the code: Use a scan tool to confirm P047C and look for related codes (especially for exhaust or DPF systems).
• 2. Inspect the wiring: Visually check the exhaust pressure sensor “B” wiring and connector for damage, corrosion, or loose pins.
• 3. Test the sensor: Using a multimeter, check the reference voltage and ground at the sensor connector. Compare sensor output voltage to OEM specs with ignition on and engine running.
• 4. Inspect sensor hoses: Remove and check hoses for carbon build-up, clogs, cracks, or leaks. Clean or replace as needed.
• 5. Check for exhaust leaks: Inspect the exhaust system upstream of the sensor for leaks that might affect pressure readings.
• 6. Substitute a known-good sensor: If possible, swap in a known-good sensor to confirm diagnosis.
• 7. Clear codes and retest: After repairs, erase trouble codes and test drive to see if P047C returns.

Possible repairs for code P047C #

Once you’ve pinpointed the cause, repairs are typically straightforward. Here are the fixes most often required for P047C:

• Replace the exhaust pressure sensor “B” if faulty
• Repair or replace damaged wiring or connectors to the sensor
• Clean or replace clogged/blocked sensor hoses or pipes
• Repair any exhaust leaks near the sensor
• ECM replacement or reprogramming (as a last resort, and only after all other causes are ruled out)

Can you drive with code P047C? #

Limited: Proceed with Caution. While many vehicles remain drivable with code P047C, ignoring it can lead to reduced engine power, higher emissions, or even DPF issues in diesels. If you experience limp mode, heavy smoke, or repeated check engine lights, schedule repairs promptly. Persistent driving with this fault may eventually cause more expensive component failures.

Vehicles most affected by code P047C #

P047C is most common in modern diesel vehicles using advanced emissions systems, especially those with diesel particulate filters (DPF) and turbochargers. The following models are frequently reported with this code:

• Ford F-Series (Super Duty diesels, 6.7L Power Stroke)
• Chevrolet Silverado / GMC Sierra Duramax diesels
• Ram 2500/3500 Cummins diesels
• Volkswagen and Audi TDI engines
• Mercedes Sprinter vans (BlueTEC diesels)
• Some heavy-duty commercial vehicles (various OEMs)

Common mistakes & best practices for code P047C #

Misdiagnosis can waste time and money. These are the most frequent errors—and the habits that help avoid them:

• Replacing the sensor without checking the hoses—carbon clogs or cracks are often the true cause.
• Ignoring wiring inspections—corroded or broken wires are a common culprit, especially in harsh climates.
• Overlooking exhaust leaks—unsealed joints or cracked pipes upstream can skew pressure readings.
• Skipping code clearing—always erase codes and retest after repairs to confirm success.
• Not checking for software updates—OEMs sometimes release ECM updates for emissions codes.

Express FAQ for code P047C #

Q1: Can a dirty DPF cause P047C?
A: Not directly, but a clogged DPF can increase exhaust pressures, potentially affecting sensor readings. However, P047C usually points to a low signal, often due to sensor or wiring issues rather than a plugged DPF.

Q2: Is an exhaust pressure sensor the same as a MAP sensor?
A: No. The exhaust pressure sensor measures exhaust gas pressure, typically in the exhaust stream, while a MAP sensor (Manifold Absolute Pressure) measures air pressure inside the intake manifold. They serve different roles and are not interchangeable.