P0471 Exhaust Pressure Sensor Range/Performance
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 from 2015. This doesn’t 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 key-on. This could be an electrical circuit fault or it could be mechanical.
The P0470 code may also be present along with P0471. The only difference between these two codes is the duration of the issue and the type of electrical/mechanical problem encountered by the sensor/circuit/engine controller. Troubleshooting steps may vary by manufacturer, gas or diesel, type of exhaust pressure sensor, and wire colors.
Related Exhaust Pressure Sensor Fault Codes:
P0470 Exhaust Pressure Sensor “A” Circuit
P0472 Exhaust Pressure Sensor “A” Circuit Low
P0473 Exhaust Pressure Sensor “A” Circuit High
P0474 Exhaust Pressure Sensor “A” Circuit Intermittent
Symptoms of a P0471 Engine Code May Include:
- Check Engine Light on
- Lack of power
- Unable to perform a manual regeneration
- If it is unable to perform regeneration.
Potential Causes
Typically, the causes for this code to set are:
- Blockage in the exhaust manifold tube to the pressure sensor
- Exhaust Gas Recirculation (EGR) system / air intake / boost air leaks
- Faulty exhaust pressure sensor
- A faulty Powertrain Control Module (PCM) might be the cause (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 finding out you’ve taken a long/wrong path.
Next, locate the exhaust pressure sensor on your specific vehicle. Once located, disconnect the tube connecting the sensor to the exhaust manifold. Try to blow through it. If you cannot, try to pass a small piece of wire through to dislodge the carbon trapped inside, causing the fault code you are experiencing. If you notice some water blown out, this could be the cause of the code.
If the tube is clear and free, 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 look corroded, burnt, or perhaps greenish compared to the normal metallic color you are 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 (the same kind used for bulb sockets and spark plug wires) and apply a small amount where the terminals make contact. Next, ensure the tube connecting the turbocharger to the intake manifold is not leaking. Visually inspect all tube connections around the turbocharger and intake manifold. Tighten all hose/band clamps.
Scan Tool
If you have a scan tool, clear the diagnostic codes from the memory and see if this code returns. If it does not, the connections were likely your problem.
If the code returns, we will need to test the sensor and its associated circuits. Typically, there are 3 wires at the exhaust pressure sensor.
Disconnect the harness going to the exhaust pressure sensor. With a Digital Volt-Ohm Meter (DVOM), test the 5V supply circuit going to the sensor to ensure it is powered (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 that checks out, verify that the exhaust pressure sensor ground is good. Connect a 12V test light to the battery positive (red terminal) and touch the other end of the test light to the ground circuit going to the exhaust pressure sensor circuit ground. If the test light does not illuminate, that would indicate a circuit problem. If it lights up, wiggle the wiring harness going to each sensor to see if the test light flickers, indicating an intermittent connection.
If all tests have passed so far and you continue to get a P0471 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.