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DTC codes / Ford codes / P1400

P1400 · FordDifferential Pressure Feedback Electronic Sensor Circuit Low Voltage

P1400 on Ford vehicles means the differential pressure feedback electronic (DPFE) sensor circuit is reporting a voltage lower than the powertrain control module (PCM) expects, which the PCM interprets as a sensor or wiring fault. The DPFE sensor measures the pressure drop across the exhaust gas recirculation (EGR) valve's metering orifice, and low voltage typically indicates a short to ground, an open circuit, or a failed sensor.

SystemPowertrain
Code typeFord specific
SeverityMedium
Fix difficultyIntermediate
AreaAuxiliary emission controls

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms
  • Slight rough idle or stumble when the EGR valve opens during light acceleration
  • Reduced fuel economy because the PCM may disable EGR and default to a richer strategy
  • Intermittent hesitation or surge at steady cruise speeds
  • Failed emissions test due to incomplete EGR monitor or stored code
  • In rare cases, a noticeable ping or spark knock under light load if EGR is disabled

Common causes, most likely first

  1. Failed DPFE sensor (internal short or degraded sensing element)
  2. Damaged or disconnected DPFE sensor electrical connector
  3. Chafed, broken, or shorted signal wire between the DPFE sensor and PCM
  4. Corroded or loose ground connection for the DPFE sensor circuit
  5. Plugged or restricted EGR pressure hoses (DPFE sense lines) causing false low readings
  6. Faulty PCM driver for the DPFE reference or signal circuit (less common)
  7. Aftermarket or incorrect DPFE sensor with wrong voltage output curve

How to diagnose and fix it

  1. Inspect the DPFE sensor connector and wiring for damage, corrosion, or loose pins; repair as needed
  2. Check the two pressure hoses from the EGR tube to the DPFE sensor for cracks, softness, or blockage; replace if suspect
  3. Measure reference voltage (typically 5V) and signal voltage at the DPFE connector with key on, engine off; compare to specification
  4. Backprobe the signal wire and monitor voltage while lightly tapping the sensor and wiggling the harness to catch intermittent faults
  5. Check for continuity and short to ground on the signal wire between the DPFE sensor and PCM; repair harness if faulty
  6. Replace the DPFE sensor if voltage checks confirm a failed sensor, then clear codes and verify EGR monitor runs
  7. If all circuits and sensor are good, diagnose the PCM driver circuit or substitute a known-good PCM for testing

DPFE sensor low voltage traps to avoid

  • A plugged or melted DPFE pressure hose can mimic a failed sensor by holding low pressure at the sensor, so always inspect the hoses before condemning the sensor.
  • Ford DPFE sensors are known for intermittent failures that only show up when hot or after a cold start, so a single voltage check may pass a failing sensor.
  • The code can set from a poor ground at the sensor mounting bolt or engine block, not just from the signal wire, so check grounds before replacing parts.
  • Replacing the DPFE sensor without clearing adaptive EGR learning can leave the PCM with skewed fuel trim and a lingering rough idle for several drive cycles.
  • Some aftermarket DPFE sensors have a different output curve than the OEM part and will set P1400 again shortly after installation, so use a quality replacement.

Can I keep driving with P1400?

You can usually drive with P1400 because the PCM disables EGR and defaults to a safe fuel strategy, but avoid heavy towing or sustained high-load driving until repaired. If you notice rough running, hesitation, or knocking, have it diagnosed promptly to prevent exhaust valve damage.

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 Ford vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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