P047D — Exhaust Pressure Sensor “B” Circuit High #

Note: The wording of this code may vary depending on the vehicle manufacturer (OEM).

• Exhaust Back Pressure Sensor “B” Circuit High (Ford, GM)
• Exhaust Gas Pressure Sensor “B” High Input (Mercedes-Benz)
• Exhaust Pressure Sensor 2 Circuit High (Chrysler, Dodge, Ram)

Summary of DTC P047D #

DTC P047D refers to a detected high electrical signal in the circuit of the Exhaust Pressure Sensor “B”. The exhaust pressure sensor, sometimes called an exhaust back pressure (EBP) sensor, is a device that monitors the pressure within the exhaust system—usually to help manage emissions and protect vital components like the turbocharger and the diesel particulate filter (DPF). The “B” designation identifies a specific sensor or bank in vehicles with multiple exhaust pressure sensors. When the Powertrain Control Module (PCM) detects a voltage signal from this sensor that is outside the expected high range, it stores code P047D and may activate the Check Engine Light. This code is particularly common on diesel engines where exhaust pressure monitoring is critical for emissions control and turbocharger performance.

Common Symptoms for DTC P047D #

A vehicle with a stored P047D code may show a variety of symptoms—or sometimes none at all, especially in the early stages. However, the following signs are often reported:

• Illuminated Check Engine Light (CEL)
• Noticeable loss of engine power, especially under load
• Reduced turbocharger boost (in turbocharged engines)
• Poor fuel economy
• Engine running in “limp” or reduced power mode
• Difficulty achieving or maintaining high speeds
• Hard starting or rough idle (less common)
• Abnormal exhaust smoke (if EBP sensor input affects EGR or turbo control)

Probable Causes for P047D (Most to Least Common) #

Several factors can trigger a high circuit reading in the exhaust pressure sensor “B”. Here’s how they usually rank in real-world diagnostics:

1. Faulty exhaust pressure sensor “B” – Internal failure or contamination causes incorrect output.
2. Wiring issues – Short to voltage or damaged harness/connectors in the sensor circuit.
3. Sensor circuit poor ground – Corroded or loose ground connections leading to elevated signal voltage.
4. Exhaust system restriction – Clogged diesel particulate filter (DPF) or blocked exhaust, leading to actual high pressure readings.
5. PCM/ECU malfunction – Rare, but a fault in the powertrain control module itself can misinterpret the sensor signal.

Step-by-Step Diagnostic Guide for P047D #

Here’s a structured approach for diagnosing P047D, whether you’re a seasoned technician or a well-equipped DIYer:

1. Verify the code: Use a scan tool to confirm P047D is present and check for related codes (especially EGR, turbo, or DPF faults).
2. Visual inspection: Examine the exhaust pressure sensor “B”, wiring, and connectors for signs of damage, corrosion, or disconnection.
3. Check sensor readings: With a scan tool, compare the live data from sensor “B” to specifications (often 0.5–4.5V range). Look for abnormally high voltage readings.
4. Inspect exhaust system: Check for restrictions or blockages (like a clogged DPF), especially if the sensor and wiring appear fine.
5. Test wiring continuity: With the ignition off, use a multimeter to check for shorts to voltage or ground in the sensor circuit.
6. Substitute known-good sensor: If possible, swap in a known-good sensor to rule out sensor failure.
7. Evaluate PCM function: If all else checks out, consider PCM diagnostics or reprogramming—rare, but possible.

Possible Repairs for P047D #

Repair strategies should target the root cause discovered during diagnosis. Typical fixes include:

• Replace exhaust pressure sensor “B” if faulty or contaminated
• Repair or replace damaged wiring/connectors in the sensor circuit
• Clean or secure sensor ground connections
• Address exhaust restrictions – clean or replace the DPF or remove blockages
• PCM/ECU repair or update – only if confirmed defective after all other steps

Can You Drive With Code P047D? #

Technically—yes, but with caution. Many vehicles will enter a reduced power mode to protect the engine and emissions system. Prolonged driving with this code can lead to increased exhaust temperatures, possible turbo damage, or even DPF clogging. If you notice significant loss of power, abnormal smoke, or other driveability issues, it’s best to limit driving and seek repairs as soon as possible.

Vehicles Most Commonly Affected by P047D #

While P047D can appear on any modern vehicle with exhaust pressure monitoring (especially diesels), it’s most often seen in:

• Ford Super Duty Diesels (F-250, F-350, F-450 with Power Stroke engines)
• Ram Trucks (2500, 3500 with Cummins engines)
• Chevrolet/GMC Duramax Diesels
• Mercedes-Benz Sprinter Vans
• Some Jeep and Dodge diesel models

Common Mistakes & Best Practices for P047D #

Misdiagnosis is common if the troubleshooting process is rushed or incomplete. Avoid these pitfalls:

• Replacing the sensor without checking wiring or exhaust restrictions
• Overlooking ground connections—a poor ground can mimic sensor failure
• Ignoring related codes (EGR, DPF, turbo) that might point to the root cause
• Skipping live data analysis—always compare sensor voltage to specifications
• Neglecting to clear codes and retest after repairs

Express FAQ: P047D #

Q: Is P047D only a diesel engine code?
A: While most common on diesel engines (due to stricter exhaust pressure monitoring), some gasoline direct injection engines can also use similar sensors and set this code.

Q: Can a dirty DPF trigger P047D?
A: Yes. If the diesel particulate filter (DPF) is clogged, back pressure rises, which can cause the sensor to register high readings—sometimes leading to a P047D code.

Q: Should I reset the code after repairs?
A: Always. After making repairs, clear the code with a scan tool and verify that it does not return during a test drive. Persistent codes may indicate an underlying issue that was missed.