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Severity: Low Code type: Manufacturer-specific (Ford)

Ford P1401 Code: DPFE Sensor Circuit High Input

The Ford DPFE sensor that measures EGR flow is sending a voltage above anything it should produce.

At a glance

Severity: 2/5 – Low2/5

Severity: Low

Meaning
DPFE Sensor Circuit High Input
System
Emission Controls · Powertrain
Safe to drive?
Yes, short term
Typical repair cost
$10–$300
DIY difficulty
Easy

The Differential Pressure Feedback EGR (DPFE) sensor on older Ford gasoline engines turns the pressure drop across a metering orifice in the EGR tube into a voltage, from well under 1 V with no flow up to a few volts at full flow. P1401 sets when the signal climbs near the 5 V reference, higher than the sensor ever outputs in normal operation. Most of the time the sensor itself is to blame: it sits right next to hot exhaust plumbing, and the older aluminum-bodied versions in particular are known for failing from heat and moisture. Less often the signal wire is shorted to the 5 V reference or the sensor's ground (signal return) has opened up. Because a high DPFE reading looks like large EGR flow to the PCM, it may cut back EGR or misjudge flow, and on some trucks a bad sensor causes rough running as the EGR valve is mis-commanded. Newer Fords use the generic P0406 for this fault instead.

Can I keep driving? Fine to drive while you arrange the fix. If the idle turns rough or the engine stumbles off the line, it's usually the EGR being mis-controlled, which isn't harmful but is worth sorting soon.

Try this first – 5-minute fix

  1. Inspect the two hoses Find the DPFE sensor, usually on a bracket near the EGR valve or throttle body, and check its two rubber hoses to the EGR tube for cracks, softening or melted spots. Replace them if they're anything but supple.
  2. Check the connector Unplug the sensor, look for green corrosion or water, clean the terminals with electrical contact cleaner and plug it back in firmly.
  3. Install a new DPFE sensor If the code returns, replace the sensor with the later plastic-bodied design, making sure each hose goes back onto the same port it came from; the ports are marked on the sensor body. It's typically two small bolts, two hoses and one connector.
  4. Clear and verify Clear the code and drive at steady highway speed so the EGR monitor can run. The code shouldn't return if the sensor was the problem.

How to read P1401

How to read P1401P11243014
  1. P Powertrain
  2. 1 Manufacturer-specific
  3. 4 Auxiliary emission controls
  4. 01 Specific fault

Symptoms

  • Check engine light with P1401
  • Rough idle or stumble on some models as EGR is mis-controlled
  • Occasional light pinging under load
  • Cracked, swollen or melted DPFE hoses visible under the hood
  • Otherwise often no noticeable change

Possible causes

Ranked by how often each cause is behind this code (editorial estimate).

  1. DPFE sensor failed internally, especially heat-damaged aluminum-bodied versions 48%
  2. Moisture or corrosion inside the sensor connector 16%
  3. Signal-return (ground) wire open, leaving the signal floating high 14%
  4. Signal wire shorted to the 5 V reference 12%
  5. Damaged or melted sensor hoses allowing condensation into the sensor 10%

Diagnosis step by step

Diagnostic flow: P14011Read DPFE voltage key on, engine off2Unplug the sensor and recheck3Test the signal return4Check sensor response

  1. Read DPFE voltage key on, engine off

    Check the DPFE PID or back-probe the signal wire. Near 4.5 V or higher with no exhaust flow confirms the high-input fault; a normal low reading means the fault is intermittent.

    Tools: OBD-II scanner, Multimeter

  2. Unplug the sensor and recheck

    With the sensor disconnected and key on, the PCM's signal reading should drop close to zero. If it stays high, the signal wire is shorted to the 5 V reference somewhere in the harness.

    Tools: OBD-II scanner, Multimeter

  3. Test the signal return

    Measure resistance from the sensor's signal-return pin to the PCM's signal ground; it should be only a few ohms. An open return leaves the sensor output floating high, which mimics a failed sensor.

    Tools: Multimeter

  4. Check sensor response

    With a good sensor installed and the engine warm, the DPFE reading should rise as EGR is commanded, for example during steady acceleration, and fall back at idle. A sensor that sits high at idle is faulty.

    Tools: OBD-II scanner

Where the parts are

Air intake and fuel metering – P140112345678
Air intake and fuel metering
  1. 1MAF sensor
  2. 2Turbocharger
  3. 3Throttle body
  4. 4Intake manifold
  5. 5Fuel injector
  6. 6EGR valve
  7. 7Fuel pump
  8. 8Thermostat

Repair options & costs

RepairDIY?Estimated cost
Replace DPFE hoses Yes $10–$60
Replace DPFE sensor Yes $60–$200
Clean or repair connector Yes $20–$120
Repair shorted or open sensor wiring No $100–$300

Rough US estimates for parts and labor; shop rates vary by region. Not a quote.

Emissions / smog test impact

Will fail

P1401 turns on the check engine light and leaves the EGR monitor incomplete, so the vehicle fails an OBD emissions test until it's repaired and the monitor has run.

Frequently asked questions

Why do Ford DPFE sensors fail so often?

They sit close to hot EGR plumbing, and exhaust gas with moisture reaches the sensing element through the hoses. The older aluminum-bodied versions were especially vulnerable; the later plastic design holds up better.

Do the hoses really matter?

Yes. Cracked or melted hoses let condensation and heat reach the sensor and cause wrong readings. A hose that has come off or is plugged sets its own Ford codes, P1405 for the upstream side and P1406 for the downstream side.

Should I buy the cheapest DPFE sensor I can find?

Quality varies a lot, and a sensor that reads slightly off can set EGR flow codes later. A reputable replacement of the updated design is the safer choice for a part this cheap.

Is P1401 the same as P0406?

Functionally yes. Ford used P1401 for a high DPFE signal on older engines and switched to the generic P0406 on later models.

Sources