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DTC codes / P04xx · Auxiliary emission controls / P0471

P0471Exhaust Pressure Sensor Range/Performance

P0471 means the powertrain control module (PCM) has detected that the exhaust pressure sensor signal is outside the expected range or is not responding correctly during key-on or running conditions. The PCM compares the sensor voltage against a modeled exhaust pressure value and sets the code when the two disagree beyond a calibrated threshold.

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

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms.
  • Reduced engine power or limp mode in some vehicles, especially those with diesel particulate filters.
  • Poor fuel economy or increased regeneration frequency on diesel engines.
  • Black smoke or excessive exhaust odor from the tailpipe.
  • Rough running or hesitation under acceleration.
  • A stored freeze-frame showing the fault occurred during a specific engine load and speed.

Common causes, most likely first

  1. Faulty exhaust pressure sensor (internal failure or contamination).
  2. Clogged or restricted exhaust pressure sensor tube or port (soot buildup common on diesel engines).
  3. Damaged, chafed, or corroded wiring or connector at the sensor.
  4. Exhaust leaks upstream of the sensor causing false pressure readings.
  5. Restricted exhaust system (plugged diesel particulate filter or catalytic converter) causing pressure to exceed expected range.
  6. PCM software issue or faulty PCM (rare).

How to diagnose and fix it

  1. Inspect the exhaust pressure sensor and its wiring for physical damage, corrosion, or loose connections.
  2. Check the sensor tube and port for blockage or soot buildup; clean or replace as needed.
  3. Perform a visual inspection of the exhaust system for leaks or restrictions upstream of the sensor.
  4. Use a scan tool to compare the exhaust pressure sensor reading with a known good gauge or with the PCM's modeled value at key-on and during running.
  5. Backprobe the sensor connector to verify reference voltage, ground, and signal voltage; repair wiring faults as necessary.
  6. If the sensor signal is erratic or out of range, replace the exhaust pressure sensor and clear the code.
  7. Verify repair by performing a road test and confirming the code does not return; check for pending codes.

Before replacing the exhaust pressure sensor

  • A clogged sensor tube or port is a very common cause of P0471 on diesel engines, and cleaning it often resolves the code without replacing the sensor.
  • Exhaust leaks upstream of the sensor can cause lower-than-expected pressure readings, leading to a false P0471.
  • On some vehicles, a restricted diesel particulate filter (DPF) can cause exhaust pressure to exceed the sensor's expected range, setting P0471 even though the sensor is good.
  • The PCM may set P0471 based on a rationality check at key-on, so a sensor that reads correctly during running can still trigger the code if it fails the key-on test.
  • Always check for technical service bulletins (TSBs) for your specific vehicle, as some manufacturers have updated software or sensor designs to address this code.

Can I keep driving with P0471?

You can usually drive with P0471, but avoid heavy acceleration or towing until it is diagnosed, because a restricted exhaust or faulty sensor can lead to reduced power and increased emissions. If the engine enters limp mode or you notice excessive smoke, have it checked promptly.

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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