OBD Guide
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P0406

EGR Sensor A Circuit High

P0406 is an OBD-II diagnostic trouble code meaning: EGR Sensor A Circuit High. Common causes: short circuit in the egr sensor wiring to power, faulty egr valve position sensor. Estimated repair cost: $11–133.

Severity
⚠️ Medium
Can you drive?
Do not drive — repair immediately
Approx. repair cost
$11–133 (est.)

Symptoms

  • Check Engine Light Is On
  • Increased fuel consumption
  • Engine knocking and knocking under load
  • Unstable idle
  • Loss of power when accelerating
  • Increased NOx content in the exhaust
  • Emissions inspection failure

Causes

  • Short circuit in the EGR sensor wiring to power
  • Faulty EGR valve position sensor
  • Contamination or mechanical failure of the EGR valve
  • Open circuit in the sensor grounding circuit
  • Problems with the connector (oxidation, corrosion)
  • ECU malfunction (rare)

How to Fix

  1. Read all error codes with the scanner and write them down
  2. Check the voltage in the EGR sensor circuit with the ignition on
  3. Check the wiring and connector of the sensor for breaks, short circuits, oxidation
  4. Measure sensor resistance and compare with specification
  5. Clean the valve and EGR channels from carbon deposits
  6. Replace the EGR position sensor if the fault is confirmed
  7. Reset the code and test drive to check the fix

Related codes

P0400P0401P0402P0403P0404P0405P0407

Error P0406 by Vehicle Brand

AcuraAudiBAICBMWBYDBuickCadillacChanganCheryChevroletChryslerCitroenDodgeDongfengExeedFAWFordForthingFotonGACGMGMCGeelyGreat WallHavalHondaHongqiHyundaiInfinitiJACJaecooJaguarJeepJetourKaiyiKiaLadaLexusLi AutoLifanLincolnLivanMazdaMercedes-BenzMercuryMitsubishiNIONissanOldsmobileOmodaOpelPeugeotPlymouthPontiacRenaultSWMSaturnSkodaSkywellSubaruSuzukiTankToyotaVolkswagenVolvoVoyahXPengZeekrZotye

FAQ

What does the P0406 code mean?

P0406 is an OBD-II diagnostic trouble code that indicates: EGR Sensor A Circuit High

What causes a P0406 error code?

The most common causes of P0406 include: Short circuit in the EGR sensor wiring to power; Faulty EGR valve position sensor; Contamination or mechanical failure of the EGR valve; Open circuit in the sensor grounding circuit.

How do I fix a P0406 diagnostic trouble code?

To fix P0406: Read all error codes with the scanner and write them down. Check the voltage in the EGR sensor circuit with the ignition on. Check the wiring and connector of the sensor for breaks, short circuits, oxidation. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P0406?

Do not drive — repair immediately

How much does it cost to fix P0406?

The estimated repair cost for P0406 is $11–133. Actual cost depends on your vehicle, location, and labor rates.

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