What does it mean?
This generic powertrain/engine diagnostic code applies to all engines using variable nozzle turbochargers (gasoline or diesel), starting around 2005 on Ford trucks with 6.0L diesel engines, all Ford EcoBoost engines, and eventually leading to the Cummins 6.7L in 2007, the 3.0L in the Mercedes lineup in 2007, and more recently the Cummins 3.0L 6-cylinder in Nissan vans starting in 2015. This does not necessarily mean you won’t get this code in a VW or other brand.
This code is strictly concerned with the incoming signal from the exhaust pressure sensor not matching the intake manifold pressure or ambient air pressure during power-up. It is strictly an electrical circuit fault.
Code P0471 may also be present along with P0472. The main difference between these two codes is that P0472 is purely electrical while P0471 can result from a mechanical or electrical fault. It is generally recommended to start with P0473 (electrical) before moving on to P0471 (electrical/mechanical) next. This way, if the problem is electrical, there is a higher likelihood of repair by starting with the electrical system.
Troubleshooting steps may vary by manufacturer, gasoline or diesel, type of exhaust pressure sensor, and wire colors.
Related Exhaust Pressure Sensor Fault Codes:
- P0470 Exhaust Pressure Sensor “A” Circuit
- P0471 Exhaust Pressure Sensor “A” Circuit Range/Performance
- P0473 Exhaust Pressure Sensor “A” High Circuit
- P0474 Exhaust Pressure Sensor “A” Circuit Intermittent
Symptoms
Symptoms of a P0472 engine code may include:
- Check Engine Light on
- Lack of power
- Unable to perform a manual regeneration – burn soot from the particulate filter. It looks like a catalytic converter but has temperature sensors and pressure sensor probes inserted in it.
- If it is unable to perform regeneration, it may eventually become a no-start condition.
Potential Causes
Typically, the causes for this code to set are:
- Open in the signal circuit between the exhaust pressure sensor and the PCM
- Open in the power supply circuit between the exhaust pressure sensor and the PCM
- Short to ground in the exhaust pressure sensor signal circuit
- Faulty exhaust pressure sensor – internal short to ground
- A Powertrain Control Module (PCM) may be faulty (very unlikely)
Diagnostic and Repair Procedures
A good starting point is always to check for a Technical Service Bulletin (TSB) for your specific vehicle. The vehicle manufacturer may have a PCM flash/reprogram to address this issue, and it’s worth checking before discovering you’ve taken a long/wrong path.
Next, locate the exhaust pressure sensor on your specific vehicle. Once located, visually inspect the connectors and wiring. Look for chafing, rubbing, bare wires, burns, or melted plastic. Separate the connectors and carefully inspect the terminals (the metal parts) inside the connectors. See if they appear corroded, burnt, or perhaps greenish compared to the normal metallic color you’re used to seeing. You can get electrical contact cleaner at any auto parts store if terminal cleaning is needed. If that’s not possible, find 91% rubbing alcohol and a soft plastic-bristled brush to clean them. Then let them air dry, get some dielectric silicone compound (same as used for bulb sockets and spark plug wires) and apply it where the terminals make contact.
If you have a scan tool, clear the diagnostic codes from memory and see if this code returns. If not, the connections were likely your problem.
If the code returns, we’ll need to test the sensor and its associated circuits. Typically, there are 3 wires to the exhaust pressure sensor.
Disconnect the harness going to the exhaust pressure sensor. With a digital voltmeter (DVOM), test the 5V supply circuit going to the sensor to ensure it has power (red wire to the 5V supply circuit, black wire to a good ground). If there are 12 volts at the sensor when there should be 5 volts, repair the wiring from the PCM to the sensor for a short to 12 volts, or possibly a faulty PCM.
If that’s okay, with a DVOM, check that the exhaust pressure sensor signal circuit is 5V (red wire to the sensor signal circuit, black wire to a good ground). If there is no 5 volts at the sensor, or if you see 12 volts at the sensor, repair the wiring from the PCM to the sensor, or again a faulty PCM.
If all tests have passed so far and you continue to get a P0472 code, this would most likely indicate a failing exhaust pressure sensor, although a faulty PCM cannot be ruled out until the sensor has been replaced.