P047E — Exhaust Pressure Sensor “B” Circuit Intermittent/Erratic #

Note: The exact wording of this code may differ depending on the vehicle manufacturer. Below are known label variations for P047E.

• Exhaust Pressure Sensor “B” Circuit Intermittent/Erratic (Generic, SAE)
• Exhaust Pressure Sensor B Intermittent/Erratic Signal (Ford)
• Exhaust Pressure Sensor B Circuit Intermittent (GM)
• Exhaust Pressure Sensor 2 Circuit Erratic (Mercedes-Benz)

Summary of Code P047E #

P047E is an OBD-II diagnostic trouble code (DTC) that indicates the vehicle’s powertrain control module (PCM) or engine control module (ECM) has detected an intermittent or erratic electrical signal from the exhaust pressure sensor “B”. This sensor is responsible for monitoring the pressure within the exhaust system—often before or after the diesel particulate filter (DPF) on diesel engines. An erratic signal means the sensor voltage is fluctuating outside the expected range, or the signal drops in and out unexpectedly. Such behavior can interfere with emissions control and engine performance. The “B” designation refers to a secondary exhaust pressure sensor if multiple sensors are present.

Common Symptoms for Code P047E #

When P047E is stored, the symptoms can range from subtle to quite noticeable. The driver may experience one or more operational issues, depending on how the exhaust pressure sensor’s data is used by the ECM. Typical symptoms include:

• Illuminated Check Engine Light
• Decreased engine performance or reduced power mode (limp mode)
• Poor fuel economy
• Rough or erratic engine idle
• DPF regeneration issues (on diesel vehicles)
• Unusual exhaust odors or visible smoke

Probable Causes for Code P047E #

There are several potential causes for an intermittent or erratic exhaust pressure sensor “B” signal. Some are more common than others, depending on vehicle age, environment, and maintenance history. These causes include:

1. Faulty exhaust pressure sensor “B” (internal sensor failure or degradation)
2. Wiring issues (chafed wires, broken connectors, poor ground, or corrosion at terminals)
3. Intermittent connection at the sensor or harness plug
4. Exhaust leaks or blockages near the sensor pickup tube
5. PCM/ECM software glitches or rare internal failure
6. Contaminated sensor (soot/carbon buildup affecting sensor operation)

Step-by-Step Diagnostic Guide for P047E #

Proper diagnosis of P047E requires a methodical approach to distinguish between a genuine sensor fault and intermittent wiring or connection issues. Here is a typical diagnostic workflow:

1. Read and record all DTCs (including pending and history codes) and freeze frame data with a scan tool.
2. Visually inspect the exhaust pressure sensor “B”, its connector, and wiring for obvious signs of damage, corrosion, or loose connections.
3. Check for exhaust leaks or blockages near the sensor and its pressure tube/hose.
4. Backprobe the sensor with a digital multimeter to monitor signal voltage while wiggling the harness and connector (looking for drops or spikes).
5. Compare live data from the exhaust pressure sensor “B” to manufacturer specs and, if applicable, to sensor “A”.
6. Test the sensor off the vehicle (bench test, if possible, per OEM procedures).
7. Check for updated PCM/ECM software (TSBs or recalls may apply).

Possible Repairs for P047E #

Based on the diagnostic outcome, several repairs may resolve P047E. Address the most likely causes first, and only replace parts after thorough testing:

• Repair or replace damaged wiring or corroded connectors to the sensor
• Clean or replace the exhaust pressure sensor “B” if contaminated or faulty
• Clean or replace the pressure pickup tube if clogged with soot
• Repair exhaust leaks near the sensor location
• Reprogram or update PCM/ECM software if an OEM fix is available
• Replace the PCM/ECM only if all other avenues are exhausted and the module is confirmed faulty (rare)

Is It Safe to Drive With Code P047E? #

Limited. While it is often possible to drive with P047E present, it is not recommended for extended periods. The code signals a problem that may cause poor engine performance, trigger limp mode, or interfere with emissions controls such as DPF regeneration on diesels. Continued driving without repair can lead to more serious issues, such as a clogged DPF or further damage to the exhaust system. It’s best to address this code as soon as possible.

Vehicles Most Commonly Affected by P047E #

While P047E can appear on any OBD-II equipped vehicle with exhaust pressure sensors, it is most frequently reported on modern diesel vehicles where exhaust pressure monitoring is critical for emissions control. Models especially prone to this code include:

• Ford F-Series Super Duty Diesels (Power Stroke engines)
• Chevrolet Silverado/GMC Sierra Duramax Diesels
• RAM Trucks with Cummins diesels
• Mercedes-Benz Sprinter (especially BlueTEC diesels)
• Volkswagen TDI models
• Some heavy-duty Isuzu and Hino trucks

Common Mistakes & Best Practices for P047E #

Misdiagnosis of P047E can lead to unnecessary parts replacement or prolonged issues. Avoid these pitfalls and follow best practices:

• Replacing the sensor without checking for wiring/connectivity problems
• Ignoring exhaust leaks or blockages that affect sensor readings
• Not using a scan tool to compare live data from multiple sensors
• Overlooking Technical Service Bulletins (TSBs) related to this code
• Failing to clear codes and confirm repair with a road test

Quick FAQ for Code P047E #

Here are answers to some common questions about P047E:

• Q: Can a dirty sensor trigger P047E?
  A: Yes. Soot or carbon buildup can cause erratic sensor readings and should be cleaned or the sensor replaced if contaminated.
• Q: Is P047E always a sensor failure?
  A: No. Wiring issues, connector problems, or even exhaust leaks can also cause this code. Always diagnose thoroughly before replacing parts.