Diesel Trouble Codes

P0471 — Exhaust Pressure Sensor A Circuit Range/Performance (6.7 Cummins (EGR + DPF, pre-SCR))

Exhaust Pressure Sensor A Circuit Range/Performance

Updated September 2, 2026

What it means

The ECM has detected the exhaust pressure sensor A signal is outside the expected range or performance.1

Most likely causes

  1. Exhaust pressure sensor A (pre-DPF/EGR pressure sensor) electrical fault or out-of-range signal — Check sensor supply voltage, ground, and signal circuit for opens/shorts and connector corrosion; compare sensor voltage to spec at key-on and idle. A biased or stuck signal can set range/performance.1
  2. Exhaust pressure sensor A wiring harness chafing/damage from heat or vibration — Inspect harness routing near exhaust/DPF and EGR components for melted insulation, chafing, or poor pin contact that alters the signal.1
  3. Exhaust system restriction or abnormal pressure affecting sensor reading — A plugged DPF, NAC, or exhaust blockage can drive pressure outside the calibrated range, leading to a range/performance fault. Verify DPF differential pressure and inspect for restriction.1
  4. ECM calibration / reference voltage issue — If multiple sensor circuits show odd values, verify ECM reference voltage and grounds before replacing the sensor.1

How to diagnose

  1. Verify code and freeze frame; confirm P0471 is present and note engine conditions.
  2. Inspect exhaust pressure sensor A connector and wiring for heat damage, corrosion, or chafing; repair as needed.
  3. Check sensor supply voltage, ground, and signal voltage at key-on and idle against service specifications; look for out-of-range or stuck values.
  4. Compare exhaust pressure readings to expected values using a scan tool; check for plausibility with DPF differential pressure and engine load.
  5. Inspect exhaust system for restriction (DPF/NAC plugging, collapsed pipe) that could cause abnormal pressure; evaluate differential pressure data.
  6. If electrical tests pass, substitute a known-good exhaust pressure sensor A and re-evaluate.
  7. Clear codes and road test under varied load to confirm repair.

Parts and tools you may need

Rough cost and difficulty

Parts cost varies by brand and labor rates; diagnostic time is typically 0.5–1.5 h plus any sensor or wiring repair.

When to see a pro

If wiring faults are extensive, the exhaust system is heavily corroded, or the DPF shows high differential pressure indicating plugging, have a diesel technician evaluate for safe repair and emissions compliance.

Sources

  1. Curated DTC seed — 6.7 Cummins (EGR + DPF, pre-SCR) (curated) ↩︎ ↩︎ ↩︎ ↩︎ ↩︎