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P1406

Differential Pressure Feedback Electronic Sensor Circuit Downstream Hose.

  • Ford
  • Powertrain
  • Manufacturer code
  • Low severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
4
AreaAuxiliary emission controls
06
FaultThe specific fault in that area

What it means

On Ford, P1406 relates to the Differential Pressure Feedback EGR (DPFE) sensor circuit, specifically the downstream hose that senses pressure on the exhaust side of the metering orifice. The engine control unit saw a DPFE signal that did not match what it expected, which usually points to a blocked, split, disconnected or swapped downstream hose or a restricted orifice tube. The sensor reading is used to measure and control EGR flow.

Symptoms

  • Engine warning light on
  • Rough or unstable idle
  • Hesitation or poor throttle response under load
  • Pinking or knocking on light acceleration
  • Slightly increased fuel consumption
  • Possible failed emissions test

Possible causes

  • Downstream hose to the DPFE sensor split, perished, disconnected or blockedlikely
  • Carbon-blocked EGR orifice tube or pressure pipe connectionslikely
  • Hoses to the DPFE sensor fitted to the wrong ports or crossed overpossible
  • Faulty DPFE sensor giving an implausible signalpossible
  • Corroded, loose or damaged sensor connector or wiring fault in the signal, reference or ground circuitpossible
  • Leaking or cracked EGR pipe or loose pipe fittings affecting the pressure readingrare
  • Fault within the engine control unitrare

How to diagnose

  1. Read the stored codes and freeze frame data, noting engine load, speed and temperature when the code set, and check for other EGR or DPFE codes.
  2. Visually inspect both DPFE hoses for splits, softness, kinks, blockages, oil or water contamination and secure fitment at both ends.
  3. Confirm the hoses are on the correct ports, with the downstream hose connected to the correct side as per the model's service information.
  4. Inspect the sensor connector and wiring for corrosion, bent pins, chafing and poor connection.
  5. With the ignition on and engine off, check the DPFE live data value against the specification for your model; it should read near its baseline and not be fixed high or low.
  6. Check the sensor's reference voltage, ground and signal at the connector using a multimeter, following the wiring diagram for the engine.
  7. Remove the pipes and inspect the orifice tube and EGR passages for carbon blockage, and check the pipe for leaks.
  8. Check the EGR valve operation and watch the DPFE reading change as EGR is commanded, as per the procedure for the specific model.

How to fix

  • Replace damaged, blocked or perished DPFE hoses and refit them to the correct ports.
  • Clean or replace the carbon-blocked EGR orifice tube and pressure pipes.
  • Repair wiring or connector faults found on the sensor circuits.
  • Replace the DPFE sensor if it fails the signal and reference checks.
  • Repair or replace any leaking EGR pipe or loose fitting, then clear the code and road test to confirm it does not return.

Can I keep driving?

Low severity

The car can usually be driven for a short time while you arrange a repair, but poor running and increased emissions may result. Book it in soon, and stop if the engine runs very roughly or knocks.

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

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