P0406: Exhaust Gas Recirculation Sensor A Circuit High
Can you still drive? Yes, you can drive safely. The EGR system will not function properly, potentially causing increased emissions and minor drivability symptoms.
What Does P0406 Mean?
Code P0406 indicates that the EGR valve position sensor is reporting a voltage that is above the expected maximum range. This is the opposite of P0405 and typically suggests an open circuit in the ground wire, a short to voltage in the signal wire, or a failed sensor sending an erroneously high signal.
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Browse OBD-II Scanners on AmazonCommon Causes
- Faulty EGR position sensor
- Open circuit in sensor ground wire
- Short to battery voltage in signal wire
- Corroded sensor connector
- Failed DPFE sensor (Ford vehicles)
Symptoms
- Check engine light on
- Rough or unstable idle
- Hesitation under acceleration
- Engine knocking or pinging
Diagnostic Steps
- 1Read EGR sensor voltage with a scan tool with key on engine off
- 2Inspect sensor wiring harness and connector for damage
- 3Check sensor ground circuit continuity with a multimeter
- 4Test for short to voltage on the signal wire
- 5Replace the EGR position sensor or DPFE sensor if wiring checks out
Recommended Parts & Tools
EGR position sensor
Estimated Repair Cost
| Type | Estimated Cost |
|---|---|
| Total Repair Cost Range | $50 - $300 |
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Chat with AI About P0406Commonly Affected Vehicles
Related Recalls
5 Active Recalls — 2026 Ford Explorer
The following NHTSA safety recalls have been issued for this vehicle. Contact your dealer to check if your vehicle is affected.
VISIBILITY:WINDSHIELD
Ford Motor Company (Ford) is recalling certain 2025-2026 Lincoln Corsair, Lincoln Aviator, and Explorer vehicles. The windshield glass may have visible air bubbles, which can obscure the driver's visibility. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 205, "Glazing Materials."
Remedy: Dealers will inspect and replace the windshield as necessary, free of charge. Owner notification letters were mailed November 6, 2025. Owners may contact Ford customer service at 1-866-436-7332. Ford's number for this recall is 25C60. Vehicle Identification Numbers (VINs) involved in this recall become searchable on NHTSA.gov beginning October 27, 2025.
ENGINE
Ford Motor Company (Ford) is recalling certain 2026 Explorer, Mustang, Lincoln Corsair, and 2025 Maverick vehicles. The cylinder head may have been improperly manufactured, which can cause the ball plugs to fail, resulting in an oil leak.
Remedy: Dealers will replace the cylinder head assembly, free of charge. All affected vehicles are still within dealership inventory and therefore no owner notification letters will be mailed. Owners may contact Ford customer service at 1-866-436-7332. Ford's number for this recall is 25SD3. Vehicle Identification Numbers (VINs) involved in this recall became searchable on NHTSA.gov on November 24, 2025.
TRAILER HITCHES
Ford Motor Company (Ford) is recalling certain 2024-2026 Explorer and 2024-2026 Lincoln Aviator vehicles. The trailer hitch assembly bolts may be loose.
Remedy: Dealers will inspect and tighten the trailer hitch bolts, or replace them as necessary, free of charge. Owner notification letters were mailed October 29, 2025. Owners may contact Ford customer service at 1-866-436-7332. Ford's number for this recall is 25SA3. Vehicle Identification Numbers (VINs) involved in this recall became searchable on NHTSA.gov on October 15, 2025.
VISIBILITY:WINDSHIELD
Ford Motor Company (Ford) is recalling certain 2026 Explorer vehicles. During manufacturing, the windshield may not have been properly bonded to the vehicle, allowing it to detach in a crash. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard (FMVSS) number 212, "Windshield Mounting."
Remedy: Dealers will remove and replace the windshield, free charge. Owner notification letters were mailed January 30, 2026. Owners may contact Ford customer service at 1-866-436-7332. Ford's number for this recall is 26C02. Vehicle Identification Numbers (VINs) involved in this recall became searchable on NHTSA.gov on January 22, 2026.
EXTERIOR LIGHTING:HEADLIGHTS
Ford Motor Company (Ford) is recalling certain 2025-2026 Explorer vehicles. The Dynamic Bending Light (DBL) system software may cause the passenger-side headlight to turn in the wrong direction when driving through curves in the road. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 108, " Lamps, Reflective Devices, and Associated Equipment."
Remedy: The headlight control module software will be updated by a dealer, or through an over-the-air (OTA) update, free of charge. Owner notification letters are expected to be mailed March 23, 2026. Owners may contact Ford customer service at 1-866-436-7332. Ford's number for this recall is 26C12. Vehicle Identification Numbers (VINs) involved in this recall became searchable on NHTSA.gov on March 5, 2026.
Data provided by the National Highway Traffic Safety Administration (NHTSA).
Frequently Asked Questions
What is the difference between P0405 and P0406?
P0405 means the EGR sensor signal is too low, while P0406 means it is too high. Both point to electrical issues in the EGR sensor circuit but have different underlying wiring faults.
Can a bad EGR sensor damage my engine?
A faulty EGR sensor itself will not damage your engine, but if the EGR valve operates incorrectly as a result, it could cause engine knock or excessive exhaust gas recirculation, which may cause issues over time.
Community Fix Reports
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