P0406 on 1997-2004 Ford F-150 (XL, XLT, Lariat, FX4, King Ranch) — Exhaust Gas Recirculation Sensor "A" Circuit High
1 vehicles · 1 makes · $50-$250 repair
How to diagnose and fix P0406: most-reported vehicles
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Ford F-150 · 1997–2004
The Delta Pressure Feedback EGR (DPFE) sensor and the EGR throttle-body spacer passages are a chronic Check-Engine source on 1997-2004 4.2L/4.6L/5.4L trucks. The ceramic DPFE sensor drifts or cracks, and the narrow 90-degree EGR elbow passages carbon up until flow is blocked, setting P0401 (insufficient EGR flow). The result is a rough idle, stumble or stall when coming to a stop, hesitation, and reduced fuel economy. It is frequently misdiagnosed as the EGR valve itself.
Common Symptoms
- Check-engine light with P0401/P0402
- Rough idle and stumble at stops
- Stalling when decelerating to a stop
- Hesitation on light acceleration
- Reduced fuel economy
How to Fix
Test the DPFE sensor voltage and manually apply vacuum to the EGR valve at idle to confirm the valve/passages are clear. Replace the DPFE sensor (inexpensive, ~15-minute job) and clean the carbon-clogged EGR tube/throttle-body spacer passages. Replace cracked vacuum lines and the EGR valve only if proven faulty.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- DPFE / EGR Pressure Feedback Sensor (bolt-mount design)OEMF77Z-9J460-AB (Motorcraft DPFE-15)Cross-refStandard Motor Products VP8, Standard Motor Products VP8T, Wells 5S2049$25–$65
Motorcraft DPFE-15 (Ford F77Z-9J460-AB) is the updated Motorola 1.0-volt silicon design that supersedes the original ceramic sensor, and RockAuto lists it for every engine
- DPFE / EGR Pressure Feedback Sensor (clip-mount design)Cross-refStandard Motor Products VP17, Wells 5S2047, NTK EA0008$22–$32
RockAuto explicitly splits these listings by mounting and by engine VIN: Wells 5S2047 and NTK EA0008 are called out as 'Engine VIN W; clip mount' on the 4.6L, while 5S2049/EA0009 are 'Engine VIN 6 or VIN W; bolt mount'.
Sources for this issue (1)
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P0406 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0406 mean?
P0406 stands for "Exhaust Gas Recirculation Sensor "A" Circuit High." The PCM reads a higher-than-expected voltage from EGR position/feedback sensor A, indicating a short to voltage, open signal, or failed sensor on an electronic EGR valve.
What are the most common causes of P0406?
The most common causes of P0406 are: Failed EGR position sensor A, Short to voltage in signal wire, Open ground circuit raising signal voltage, Corroded or damaged EGR connector, Faulty PCM (rare). The specific cause varies by vehicle.
How much does it cost to fix P0406?
Repair costs for P0406 range from $50 to $250, depending on the vehicle and root cause.
Which vehicles are affected by P0406?
Au7o has documented P0406 across 1 vehicle models from 1 manufacturers: Ford.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.