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DTC codes / P04xx · Auxiliary emission controls / P047D

P047DExhaust Pressure Sensor B Circuit High

P047D means the powertrain control module (PCM) has detected a high-voltage condition on the signal circuit for Exhaust Pressure Sensor B, which is typically a differential pressure sensor used to monitor the diesel particulate filter (DPF). The sensor's output voltage is above the normal range for the current operating conditions, indicating a short to voltage, an open ground, or a sensor that has failed internally.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaAuxiliary emission controls

Symptoms you may notice

  • Illumination of the check engine light (malfunction indicator lamp) with no other noticeable symptoms
  • Reduced engine power or limp mode, especially on diesel vehicles with an active DPF regeneration strategy
  • Frequent or failed DPF regeneration cycles, leading to soot accumulation and eventual derate
  • Poor fuel economy or increased exhaust smoke due to incorrect pressure readings affecting fuel delivery
  • A stored code for DPF efficiency or regeneration performance, such as P2002 or P2463, appearing alongside P047D

Common causes, most likely first

  1. Exhaust pressure sensor B has failed internally and is outputting a voltage higher than the actual pressure warrants
  2. Short to voltage on the sensor signal circuit, often from chafed wiring near the exhaust or turbocharger
  3. Open or high-resistance ground circuit for the sensor, causing the signal voltage to float high
  4. Corroded or damaged connector pins at the sensor or PCM, introducing resistance that skews the signal
  5. A faulty PCM driver or internal pull-up resistor on the sensor signal circuit, though this is less common
  6. Exhaust system blockage or a kinked pressure hose that causes the sensor to read a false high pressure, though this usually sets a low or performance code rather than a high circuit code

How to diagnose and fix it

  1. Connect a scan tool and verify P047D is current, then check freeze-frame data for sensor B voltage and compare it to key-on, engine-off and idle readings to confirm the high signal
  2. Visually inspect the sensor B connector, wiring harness, and pressure hoses for chafing, corrosion, or disconnection, especially near hot exhaust components
  3. Measure reference voltage and ground at the sensor connector with a digital multimeter; a good ground should read less than 0.1 volt drop and the reference should be near 5 volts
  4. Back-probe the signal wire at the sensor and at the PCM to check for a short to voltage or an open circuit, wiggle-testing the harness while watching the meter
  5. If wiring and grounds check out, substitute a known-good sensor B and clear the code to see if it returns, confirming whether the sensor itself is at fault
  6. Check for technical service bulletins (TSBs) or software updates for the PCM that address false P047D setting, as some manufacturers have released calibration fixes
  7. After repair, clear codes and perform a DPF regeneration or drive cycle to verify the repair and ensure no related codes return

What a high exhaust pressure code really means

  • A high circuit code does not always mean the sensor is bad; a poor ground at the sensor can cause the signal voltage to float high, mimicking a failed sensor and leading to unnecessary replacement.
  • On many diesel vehicles, Exhaust Pressure Sensor B is the DPF differential pressure sensor, and a high signal can be set by a restricted pressure hose or a clogged DPF port rather than an electrical fault, so always inspect the pressure paths.
  • Intermittent P047D codes often trace to wiring chafing against the firewall or exhaust heat shields, which only shorts when the engine moves under load, so a wiggle test while monitoring live data is essential.
  • Some PCMs set P047D during a forced DPF regeneration if the sensor signal exceeds a threshold momentarily, and the code may be a symptom of an overactive regeneration rather than a hard sensor failure.
  • Replacing the sensor without checking the ground circuit is a common misdiagnosis; a voltage drop test on the ground side takes minutes and can save the cost of a part that was never faulty.

Can I keep driving with P047D?

You can usually drive the vehicle short distances to a repair shop, but avoid heavy loads and long trips because a false high exhaust pressure reading can disrupt DPF regeneration and lead to a derate or filter damage. If the engine enters limp mode or you notice excessive smoke, stop driving and seek professional diagnosis.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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