P1406

DPFE Circuit High Input

Powertrain Emission Controls EGR System 🟡 Moderate — Fix within a week ⚠️ Drive with Care
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What This Actually Means

In plain language — no jargon

The exhaust gas recirculation (EGR) feedback sensor is sending a voltage signal that's too high, like a thermometer reading way above normal. This means the sensor or its circuit isn't working properly and needs attention.

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Symptoms You May Notice

3 known symptoms for this code
Check Engine Light illuminated
Rough idle or hesitation during acceleration
Increased emissions or failed emissions test
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How Your ECU Detects This

Technical sensor logic and voltage thresholds

The ECU monitors voltage from the DPFE (Differential Pressure Feedback EGR) sensor, which measures exhaust backpressure to control EGR flow. When the voltage signal exceeds the maximum threshold (typically 4.5-4.8V), the ECU triggers a fault because it indicates a sensor malfunction or wiring issue.

Voltage & Parameter Thresholds

ParameterNormal RangeFault Condition
DPFE Sensor Voltage 0.5V to 4.5V Above 4.8V
EGR Flow Rate Within calibrated range Cannot be verified or controlled
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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex
1
Wiring and connector inspection
Check DPFE sensor connector for corrosion, loose pins, or damaged wires; clean or reseat connections.
2
DPFE sensor replacement
Unbolt the sensor from the EGR valve assembly and replace with a new unit if voltage remains high after wiring checks.
3
EGR valve or lines
Inspect EGR tubes and valve for blockage or leaks that may cause abnormal pressure readings.
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When to See a Professional Mechanic

Not all fault codes are safe to DIY

Code P1406 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.

Safety note: OBD-II codes identify the system or circuit where a fault was detected — they do not always identify the exact failed component. A professional mechanic using live sensor data will diagnose the root cause more accurately than replacing parts based on the code alone.
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How to Clear Code P1406

What happens after you fix the fault

Once the fault is repaired, P1406 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.

The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.

✅ Safe to Clear When
  • Fault has been diagnosed and repaired
  • You want to confirm the repair worked
  • Code appeared after a sensor was cleaned
⚠️ Do Not Clear When
  • Preparing for an emissions/PUC test
  • Root cause is still undiagnosed
  • Check engine light is flashing
Emissions test note: Clearing codes resets OBD readiness monitors. Most vehicles need 50–100 km of mixed driving before monitors complete. Do not clear codes immediately before an emissions or PUC inspection.