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P1401

DPFE Sensor Circuit High Input.

  • Mazda
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
4
AreaAuxiliary emission controls
01
FaultThe specific fault in that area

What it means

On Mazda, P1401 means the powertrain control module has seen a DPFE (Differential Pressure Feedback EGR) sensor signal that is higher than expected. The DPFE sensor measures the pressure drop across a metering orifice in the EGR system to work out how much exhaust gas is flowing. The code is set when the sensor voltage stays above its normal range, which points to a sensor, wiring, or hose or pipe problem in the EGR feedback circuit.

Symptoms

  • Check engine light on
  • Rough or unstable idle
  • Hesitation or surging under light load
  • Pinging or knocking (detonation) under load
  • Poor fuel economy
  • Possible stalling at idle or when slowing down

Possible causes

  • Faulty DPFE sensor giving a high output voltagelikely
  • Blocked, split, disconnected or swapped hoses to the DPFE sensor, or a blocked sensor portlikely
  • Carbon-blocked EGR metering orifice or EGR pipe giving a false pressure readingpossible
  • Signal wire short to the reference or supply voltage, or a high-resistance fault in the sensor groundpossible
  • Corroded or damaged connector terminals at the sensor or control modulepossible
  • EGR valve stuck open or leaking, or exhaust leak near the EGR pipe affecting the pressure signalrare
  • Faulty powertrain control modulerare

How to diagnose

  1. Read all stored and pending codes and the freeze frame data, noting engine load, speed and temperature when the fault set. Check for other EGR or sensor supply codes.
  2. Visually inspect the DPFE sensor, its connector and the wiring for damage, chafing, corrosion or heat damage.
  3. Inspect the vacuum and pressure hoses between the sensor and the EGR pipe for cracks, blockages, soot build-up, or incorrect routing. Check that the sensor ports are clear.
  4. With the key on and engine off, read the DPFE sensor live data. It should sit at a low, stable value near atmospheric pressure. Compare against the specification for your model and engine.
  5. Check the sensor's 5 volt reference, ground and signal wires for continuity, shorts to voltage and shorts to each other, following the wiring diagram for the model.
  6. With the engine running, command or open the EGR (as the system allows) and watch whether the sensor reading changes smoothly. A reading stuck high suggests a sensor or circuit fault.
  7. Inspect the EGR valve, metering orifice and pipe for carbon blockage or leaks. Procedure varies by model and engine.
  8. If the wiring, hoses and sensor all test correctly, check the control module power, grounds and connector pins before suspecting the module.

How to fix

  • Replace the DPFE sensor if its output is stuck high or fails the live data tests.
  • Replace or correctly reroute any damaged, blocked or disconnected hoses and clear the sensor ports.
  • Clean or replace the carbon-blocked EGR orifice, pipe or EGR valve as needed.
  • Repair any short, open or high resistance in the signal, reference or ground wiring, and clean or renew faulty connector terminals.
  • Repair any exhaust leak affecting the EGR pipe or sensor readings.
  • Replace or reprogram the control module only after all other causes have been confirmed as sound.

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but book it in soon. Poor EGR control can cause pinging, rough running and higher emissions, and stalling is possible, so avoid heavy loads and long trips until it is repaired.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

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