DPFE Sensor Circuit Low Voltage
What it means
This is a Ford, Lincoln and Mercury code; the same number can mean something different on other makes. The DPFE sensor measures the pressure difference in the EGR tube through two hoses to calculate EGR flow, and the code means its signal voltage is below the normal limit. It is roughly equivalent to generic P0405, and the cause is usually the sensor, its wiring or its reference voltage.
Models covered: Ford (and Lincoln/Mercury) models with a DPFE-type EGR system, mainly around 1996–2004.
Symptoms3
- Check engine light on.
- The computer may disable EGR, causing light pinging under load.
- Often little change in driving.
Possible causes5
- Failed DPFE sensor, a well-known fault on these models.
- Loss of the 5-volt reference supply to the sensor.
- Open signal wire or signal shorted to ground.
- Corroded or loose sensor connector.
- Engine computer fault (rare).
How to diagnose5
- Read the DPFE signal voltage on a scan tool, key on and engine off, and compare with the manufacturer specification.
- Measure the reference voltage and ground at the sensor connector.
- Check the signal wire for continuity and for a short to ground.
- Inspect the connector for corrosion.
- Confirm the two sensor hoses are intact, even though this code is mainly electrical.
How to fix4
- Clean the connector or repair the damaged wire.
- Fix the reference voltage problem if it is missing.
- Replace the DPFE sensor, ideally with new hoses if they are cracked.
- Clear the code and confirm the sensor reading is normal.
Repair cost
In Saudi riyals; the highlighted part is the expected range for this fault.
The cost is low for a connector or wire repair, and a little higher for a new DPFE sensor and hoses.
Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026
Frequently asked questions
Do DPFE sensors fail often on Fords?
Yes. It is a common fault on Fords of that period, and the sensor degrades with heat and moisture over time.
Can P1400 affect other sensors?
If the cause is a shorted reference line, other sensors sharing that line may also set codes, which points the check to the wiring.
This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.
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