EN

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

Ford P1400 Code: DPFE Sensor Circuit Low Input

The Ford PCM sees the EGR pressure-feedback (DPFE) sensor signal stuck below its normal minimum voltage.

At a glance

Severity: 2/5 – Low2/5

Severity: Low

Meaning
DPFE Sensor Circuit Low Input
System
Emission Controls · Powertrain
Safe to drive?
Yes, short term
Typical repair cost
$20–$1,400
DIY difficulty
Moderate

Many Ford gasoline engines built through the mid-2000s measure EGR flow with a Differential Pressure Feedback EGR (DPFE) sensor. It reads the pressure difference across a small orifice in the EGR tube through two rubber hoses and sends the PCM a voltage that rises as more exhaust gas flows. With the key on and no EGR flow, a healthy sensor sits at a low but definite voltage, roughly 0.45 V to 1 V depending on the sensor design. P1400 means the signal fell below the lowest plausible value, which points to an electrical problem: an open signal wire, a signal shorted to ground, a missing 5 V reference, or a sensor that has failed internally. Without a valid reading the PCM can't meter or verify EGR, so it usually stops using it. Later Ford models report the same fault as the generic P0405, and it's found on vehicles like the Taurus, Ranger, Explorer, F-150, Windstar and Crown Victoria.

Can I keep driving? Safe to drive in the short term. Without EGR, combustion runs hotter, so you may hear spark knock (pinging) when accelerating uphill or under load; use the recommended octane and avoid heavy towing until it's fixed.

How to read P1400

How to read P1400P11243004
  1. P Powertrain
  2. 1 Manufacturer-specific
  3. 4 Auxiliary emission controls
  4. 00 Specific fault

Symptoms

  • Check engine light with P1400
  • Light pinging or spark knock under acceleration or load
  • Usually no other drivability change
  • Other codes for the 5 V reference circuit if the reference is shorted (throttle position, MAP/BARO or fuel tank pressure)
  • Possible P0401 after a few drives because EGR flow can't be confirmed

Possible causes

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

  1. DPFE sensor failed internally with a low or zero output 34%
  2. Connector unplugged, corroded or with a spread terminal 20%
  3. Signal wire open or shorted to ground between sensor and PCM 18%
  4. 5 V reference missing or pulled down by another sensor sharing the circuit 16%
  5. Wiring melted against the exhaust or EGR tube 8%
  6. PCM fault (rare) 4%

Diagnosis step by step

Diagnostic flow: P14001Check for companion codes2Read the DPFE value key on, engineoff3Measure the 5 V reference4Test the signal circuit5Substitute the sensor

  1. Check for companion codes

    Scan for other stored codes. If throttle position, MAP/BARO or fuel tank pressure codes are present too, suspect the shared 5 V reference circuit before the DPFE sensor itself.

    Tools: OBD-II scanner

  2. Read the DPFE value key on, engine off

    Look at the DPFE PID or back-probe the signal wire. A reading near 0 V confirms the low-input fault; a normal idle-range reading means the problem is intermittent, so wiggle the harness while watching.

    Tools: OBD-II scanner, Multimeter

  3. Measure the 5 V reference

    Unplug the sensor and measure between the reference and signal-return pins with the key on; you should see about 5 V. If it's missing, unplug other sensors on the reference circuit one at a time until it comes back, which identifies the one dragging it down.

    Tools: Multimeter

  4. Test the signal circuit

    With the sensor unplugged and the key off, check the signal wire for continuity to the PCM and for any short to ground. Follow the harness past the EGR tube and exhaust, where the insulation often melts.

    Tools: Multimeter, Flashlight

  5. Substitute the sensor

    If reference and wiring check out, the sensor has failed. Install a new DPFE, preferably the later plastic-bodied design, and replace both rubber hoses at the same time since they harden and crack.

    Tools: Screwdriver, Pliers

Where the parts are

Ignition: coils and spark plugs per cylinder – P14001234567
Ignition: coils and spark plugs per cylinder
  1. 1Ignition coil
  2. 2Spark plug
  3. 3Fuel injector
  4. 4Camshaft sensor
  5. 5Crankshaft sensor
  6. 6Engine computer (ECM)
  7. 7Intake manifold

Repair options & costs

RepairDIY?Estimated cost
Replace DPFE sensor and hoses Yes $80–$220
Clean or repair DPFE connector Yes $20–$120
Repair signal or reference wiring No $100–$300
Replace a shorted sensor on the shared 5 V circuit Yes $90–$300
Replace or reprogram PCM No $600–$1,400

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

Emissions / smog test impact

Will fail

P1400 turns on the check engine light and the EGR monitor can't complete, so the vehicle fails an OBD emissions test. After the repair, drive until the EGR monitor shows ready.

Frequently asked questions

Is P1400 the same as P0401?

No. P0401 says EGR flow is too low even though the sensor works. P1400 says the sensor signal itself is electrically too low, so the PCM can't judge EGR flow at all. P1400 should be fixed first.

Why do throttle and MAP codes show up with P1400?

Several Ford sensors share one 5 V reference from the PCM. If any of them shorts that reference, all of them lose power at once and each sets its own low-input code.

My newer Ford shows P0405 instead. Same problem?

Essentially yes. Ford moved to the generic numbering on later models, and P0405 describes the same low-voltage condition on the EGR feedback sensor circuit.

Can I clean the DPFE sensor?

No. The sensing element is sealed inside. You can clear blocked hoses, but a sensor with a failed internal element has to be replaced.

Sources