Technical Description of OBD-II Trouble Code
The input for this code is a low signal from the exhaust pressure sensor “B” that does not match the intake manifold pressure or ambient air pressure at key on. This indicates an electrical circuit fault.
Code P047B may be present along with P047C, but the main difference is that P047C is strictly an electrical fault while P047B can be caused by a mechanical or electrical issue. It is recommended to address the P047C first, as it is more likely to be resolved by addressing the electrical problem.
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 vehicle.
A typical exhaust pressure sensor:
Related trouble codes for exhaust pressure sensor “B” include:
Symptoms
Symptoms of a P047C engine code may include:
Potential Causes
The common causes for this code are:
Diagnostic and Repair Procedures
Start by checking for any technical service bulletins (TSBs) related to your vehicle. The manufacturer may have a PCM flash/reprogram to address this issue.
Next, locate the Exhaust Pressure Sensor on your vehicle and visually inspect the connectors and wiring for any damage. Clean the terminals if necessary and apply dielectric silicone compound to prevent corrosion.
If you have a scan tool, clear the diagnostic trouble codes and see if the code returns. If it does not, the issue was likely with the connections.
If the code persists, test the sensor and its associated circuits using a Digital Volt Ohm Meter (DVOM). Check the power supply circuit and the signal circuit to ensure they have the correct voltage. If there are any issues, repair the wiring or consider a possible PCM failure.
If all tests pass and the P047C code continues to appear, it is likely that the Exhaust Pressure sensor has failed and should be replaced. However, a failed PCM cannot be ruled out until the sensor is replaced.
