P047C Low input level sensor B exhaust pressure
Content
P047C Low input level sensor B exhaust pressure
OBD-II DTC Datasheet
Low level of input signal of the sensor of pressure of exhaust gases "B"
What does this mean?
This Generic Powertrain / Engine DTC applies to all engines using variable nozzle turbochargers (gas or diesel) since about 2005 on Ford trucks equipped with 6.0L diesel engines, all Ford EcoBoost engines, and ultimately eventually leads to the Cummins 6.7 L model. 2007, 3.0L in Mercedes lineup in 2007 and recently here Cummins 3.0L 6-cylinder in Nissan pickups starting in 2015. This does not mean that you will not necessarily get this code on a VW or other model.
This code strictly refers to the fact that the input signal from the exhaust pressure sensor does not match the intake manifold pressure or ambient pressure when the key is turned on. This is strictly an electrical circuit malfunction.
P047B can also be present at the same time as P047C. The main difference between the two codes is that P047C is electrical only and P0471 could be the result of a mechanical or electrical fault. It is generally recommended to start with P047C (electrical) first and then move on to P047B (electrical / mechanical). Thus, if the problem is electrical, the likelihood of repairs, starting with electrical, is increased.
Troubleshooting steps may vary depending on the manufacturer, gasoline or diesel, type of exhaust pressure sensor and wire colors. Consult your specific vehicle repair manual to determine which sensor “B” your specific vehicle has.
Typical Exhaust Pressure Gauge: 
Corresponding Exhaust Gas Pressure Sensor "B" DTCs:
- P047A Exhaust Gas Pressure Sensor B Circuit
- P047B Exhaust Gas Pressure Sensor "B" Circuit Range / Performance
- P047D A high indicator of the sensor "B" exhaust pressure
- P047E Exhaust Gas Pressure Sensor B Circuit Malfunction
symptoms
Symptoms of a P047C engine code may include:
- Check Engine light is on
- Lack of power
- Unable to perform manual regeneration - burn the particulate filter from the particulate filter. Looks like a catalytic converter, but it has temperature sensors and pressure sensors inserted into it.
- If regeneration fails, a non-cranking start may eventually occur.
Possible reasons
Usually the reason for installing this code is:
- Open in signal circuit between exhaust pressure sensor and PCM
- Open in the power circuit between the exhaust pressure sensor and the PCM
- Short circuit on weight in the signal circuit of the exhaust gas pressure sensor
- Faulty exhaust gas pressure sensor - internal short to ground
- Powertrain Control Module (PCM) may have failed (unlikely)
Diagnostic and repair procedures
A good starting point is always to find a Technical Service Bulletin (TSB) for your specific vehicle. The vehicle manufacturer may have a flash memory / PCM reprogramming to fix this problem and it's worth checking it out before you find yourself on the long / wrong path.
Then find the exhaust pressure sensor on your specific vehicle. Once detected, visually inspect the connectors and wiring. Look for scuffs, scuffs, exposed wires, burn marks, or molten plastic. Disconnect the connectors and carefully inspect the terminals (metal parts) inside the connectors. See if they look rusty, burnt, or possibly green compared to the usual metallic color you're probably used to seeing. If terminal cleaning is required, you can purchase electrical contact cleaner at any parts store. If this is not possible, find 91% rubbing alcohol and a light plastic bristle brush to clean them. Then let them air dry, take a dielectric silicone compound (the same material they use for bulb holders and spark plug wires) and place where the terminals make contact.
If you have a scan tool, clear the diagnostic trouble codes from memory and see if the code returns. If this is not the case, then there is most likely a connection problem.
If the code returns, we will need to test the sensor and associated circuits. There are usually 3 wires on the exhaust pressure sensor.
Disconnect the harness from the exhaust pressure sensor. Use a digital volt ohmmeter (DVOM) to check the 5V power supply circuit going to the sensor to make sure it is on (red wire to 5V power supply circuit, black wire to good ground). If the sensor is 12 volts when it 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 this is normal, with the DVOM, make sure you have 5V on the exhaust pressure sensor signal circuit (red wire to sensor signal circuit, black wire to good ground). If there is no 5 volts on the sensor, or if you see 12 volts on the sensor, repair the wiring from the PCM to the sensor, or again, possibly a faulty PCM.
If this is normal, with the DVOM, make sure you have 5V on the exhaust pressure sensor signal circuit (red wire to sensor signal circuit, black wire to good ground). If there is no 5 volts on the sensor, or if you see 12 volts on the sensor, repair the wiring from the PCM to the sensor, or again, possibly a faulty PCM.
If all tests have passed so far and you keep getting the P047C code, it most likely indicates a faulty exhaust pressure sensor, although the failed PCM cannot be ruled out until the sensor is replaced.
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