P1406

Ford

DPFE Sensor Downstream Hose Off Or Plugged

Definition source: Manufacturer reference catalog
Definition verification: Not independently verified for display.
Time: Varies by diagnosis and vehicle | Diagnostic difficulty: Medium
Medium Severity

The DPFE sensor measures pressure changes in the EGR passage so the engine computer can assess EGR flow. This code points to a downstream hose that is disconnected or plugged, which can distort the pressure signal and interfere with EGR monitoring. The code identifies a detected condition; it does not by itself prove the sensor needs replacement.

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⚠️ Before You Begin (Safety First)

A disconnected or plugged hose can affect emissions and may contribute to rough running or stalling. If the engine stalls or runs too poorly to drive safely, stop driving and arrange diagnosis. Let the engine and nearby exhaust parts cool before inspecting hoses.

Common Symptoms

  • The check-engine light may be on because the engine computer detected an abnormal DPFE pressure signal.
  • There may be no noticeable change in how the vehicle runs.
  • Rough running or hesitation may occur if EGR flow is not being monitored or controlled correctly.
  • Stalling may occur in some cases if the underlying EGR-related problem affects engine operation.
  • The vehicle may fail an emissions inspection because the fault concerns EGR monitoring.

Common Causes

  • The DPFE sensor's downstream hose has come off or is not seated securely.
  • The downstream hose is plugged, restricting the pressure signal reaching the sensor.
  • The hose is cracked, heat-damaged, or routed incorrectly, creating a misleading pressure signal.
  • A DPFE sensor, wiring, or EGR-flow problem may produce readings that resemble a hose fault and should be checked before parts are replaced.

Diagnostic Steps

  1. Park safely, switch off the engine, and let the engine and exhaust area cool before touching hoses.
  2. Find the DPFE sensor and its hoses using service information for the vehicle's year and engine; do not assume the same layout applies to every Ford.
  3. Check that the downstream hose is connected at both ends and routed as specified. Reconnect a loose hose only if its correct routing is clear.
  4. Look for a plugged, cracked, softened, or heat-damaged hose. Do not force debris toward the sensor or apply pressure directly to it.
  5. If the hose appears clear and properly connected, avoid replacing the sensor based on the code alone; have the DPFE signal, wiring, and EGR operation checked.
  6. After any repair, confirm the fault does not return using an appropriate scan tool and vehicle-specific procedure.

When to Call a Professional

Inspect the downstream hose for correct routing, secure connections, blockage, and heat damage. Use scan data and the vehicle-specific service procedure to assess whether the DPFE signal responds appropriately as EGR flow changes. Check for wiring, sensor, or EGR-flow problems that could mimic a hose fault before replacing parts.

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Commonly Asked Questions

Does P1406 prove the DPFE sensor is bad?

No. The code points to a downstream hose that is off or plugged. Inspect the hose and verify the sensor signal and related wiring before replacing the sensor.

What does the DPFE sensor do?

It measures pressure changes associated with EGR flow. The engine computer uses that signal to assess whether EGR flow is occurring as expected.

Can a plugged or disconnected hose cause drivability symptoms?

It can interfere with EGR monitoring and may be associated with rough running, hesitation, or stalling, but some vehicles may show no obvious symptoms.

Can I keep driving with this code?

If the vehicle runs normally, the code alone does not establish that it is unsafe to drive, but prompt diagnosis is sensible. Stop if it stalls or runs too poorly to drive safely.

Does clearing the code fix the problem?

No. Clearing the code does not repair a loose or plugged hose. Confirm the hose condition and check that the fault does not return after the repair.

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