Technical Description of OBD-II Trouble Code
High Input from Exhaust Pressure Sensor
What does that signify?
This generic powertrain/engine diagnostic trouble code is applicable to all engines that utilize variable nozzle turbochargers (gas or diesel). It was first introduced in 2005 on Ford trucks equipped with 6.0L diesel engines, all Ford EcoBoost engines, and later extended to the Cummins 6.7L in 2007, the 3.0L in the Mercedes lineup in 2007, and most recently the Cummins 3.0L 6 cyl in the Nissan pickups starting in 2015. However, it is possible to encounter this code in other makes such as VW.
This code specifically focuses on the discrepancy between the incoming signal from the exhaust pressure sensor and the intake manifold pressure or ambient air pressure during key on. It is solely an electrical circuit fault.
Code P0471 may also be present simultaneously with P0473. The main distinction between these two codes is that P0473 is purely electrical, whereas P0471 can result from either a mechanical or electrical fault. It is generally recommended to address the P0473 (electrical) first before proceeding to the P0471 (electrical/mechanical). This approach increases the likelihood of resolving the issue if it is indeed electrical.
The troubleshooting steps may vary depending on the manufacturer, whether it is a gas or diesel engine, the type of exhaust pressure sensor, and the wire colors.
A typical exhaust pressure sensor:
Related trouble codes for the exhaust pressure sensor:
Symptoms
The symptoms associated with a P0473 engine code may include:
Potential Causes
The typical causes for triggering this code are:
Diagnostic and Repair Procedures
A good starting point is always to search for any relevant technical service bulletins (TSBs) for your specific vehicle. The vehicle manufacturer may have a PCM flash/reprogram available to address this issue, so it is worth checking before embarking on a potentially lengthy and incorrect troubleshooting path.
Next, locate the Exhaust Pressure Sensor on your particular vehicle. Once found, visually inspect the connectors and wiring. Look for any signs of chafing, rubbing, bare wires, burn spots, or melted plastic. Separate the connectors and carefully examine the terminals (the metal parts) inside. Check for signs of corrosion, burning, or a greenish color, which deviates from the normal metal color. If necessary, use Electrical Contact cleaner or 91% rubbing alcohol and a light plastic bristle brush to clean the terminals. Afterward, allow them to air dry and apply some dielectric silicone compound (the same substance used for light bulb sockets and spark plug wires) where the terminals make contact.
If you have a scan tool, clear the diagnostic trouble codes from memory and observe if this code reappears. If it does not, then the issue was most likely related to the connections.
If the code does return, further testing of the sensor and its associated circuits is necessary. Typically, there are 3 wires connected to the Exhaust Pressure sensor.
Disconnect the harness connected to the Exhaust Pressure Sensor. Using a Digital Volt Ohm Meter (DVOM), test the 5V power supply circuit going to the sensor to ensure that it is receiving power (Red lead to the 5V power supply circuit, black lead to a good ground). If there is 12 volts instead of 5 volts reaching the sensor, repair the wiring from the PCM to the sensor for a short to 12 volts or consider the possibility of a faulty PCM.
If that is satisfactory, use a DVOM to check if there is 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 instead of 5 volts, repair the wiring from the PCM to the sensor or once again consider the possibility of a faulty PCM.
If that is also satisfactory, verify that there is a good ground connection at the Exhaust Pressure sensor. Connect a test light to the positive terminal of a 12V battery and touch the other end of the test light to the ground circuit connected to the Exhaust Pressure Sensor circuit ground. If the test light does not illuminate, it indicates a problem with the circuit. If it does illuminate, wiggle the wiring harness connected to the exhaust pressure sensor to check if the test light flickers, indicating an intermittent connection.
If all the tests conducted so far pass, and the P0473 code continues to appear, it is highly likely that the Exhaust Pressure sensor has failed. However, the possibility of a failed PCM cannot be ruled out until the sensor is replaced.
