Technical Description of OBD-II Trouble Code
The input for this code is the exhaust pressure sensor, which is experiencing a high input signal. This code is applicable to various engines with variable nozzle turbochargers, such as Ford trucks with 6.0L diesel engines, Ford EcoBoost engines, Cummins 6.7L and 3.0L engines, and Mercedes 3.0L engines. It may also occur in other vehicle makes.
The code specifically indicates a mismatch between the incoming signal from the exhaust pressure sensor and the intake manifold pressure or ambient air pressure during key on. This is solely an electrical circuit issue.
Code P047B may be present alongside P047D. The main difference is that P047D is purely electrical, while P047B can result from a mechanical or electrical fault. It is recommended to address the P047D (electrical) first before moving on to the P047B (electrical/mechanical) for a higher chance of repair if the issue is electrical.
Troubleshooting steps may vary depending on the manufacturer, fuel type, type of exhaust pressure sensor, and wire colors. Consult a vehicle-specific repair guide to identify the “B” sensor for your particular vehicle.
A typical exhaust pressure sensor:
Related trouble codes for exhaust pressure sensor “B”:
Symptoms
The symptoms of a P047D engine code may include:
Potential Causes
The typical causes for this code are:
Diagnostic and Repair Procedures
Start by searching for a technical service bulletin (TSB) specific to your vehicle. The vehicle manufacturer may have a PCM flash/reprogram to address this issue, so it’s worth checking before pursuing other avenues.
Next, locate the exhaust pressure sensor on your vehicle and visually inspect the connectors and wiring. Look for any signs of damage such as chafing, rubbing, bare wires, burn spots, or melted plastic. Disconnect the connectors and inspect the terminals inside for corrosion, burns, or unusual discoloration. If cleaning is necessary, use electrical contact cleaner or rubbing alcohol and a light plastic bristle brush. After cleaning, let the terminals air dry and apply dielectric silicone compound to ensure proper contact.
If you have a scan tool, clear the diagnostic trouble codes from memory and see if the code returns. If it doesn’t, the issue was likely related to the connections.
If the code does return, further testing of the sensor and its circuits is necessary. Typically, the exhaust pressure sensor has 3 wires.
Disconnect the harness going to the exhaust pressure sensor and use a Digital Volt Ohm Meter (DVOM) to test the 5V power supply circuit (red lead to the 5V power supply circuit, black lead to a good ground). If there is 12 volts instead of 5 volts, repair the wiring from the PCM to the sensor for a short to 12 volts or consider a possible PCM failure.
If the power supply circuit is functioning correctly, use the DVOM to check for 5V on the exhaust pressure sensor signal circuit (red lead to the sensor signal circuit, black lead to a good ground). If there is no 5 volts or if you measure 12 volts, repair the wiring from the PCM to the sensor or consider a possible PCM failure.
Next, check for a good ground at the exhaust pressure sensor. Connect a test light to the positive terminal of a 12V battery and touch the other end to the ground circuit of the exhaust pressure sensor. If the test light doesn’t illuminate, there is a problem with the circuit. If it does illuminate, wiggle the wiring harness going to the sensor to check for intermittent connections.
If all tests have been passed and the P047D code persists, it is likely that the exhaust pressure sensor has failed. However, the possibility of a failed PCM cannot be ruled out until the sensor is replaced.
