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Engine-Codes – Generic – P0406

P0406 Code - Exhaust Gas Recirculation Sensor 'A' Circuit High

Quick Answer

The P0406 diagnostic trouble code indicates a problem with the Exhaust Gas Recirculation (EGR) sensor 'A' circuit on the vehicle. Common causes include Faulty EGR sensor 'A', Wiring issues or a poor connection in the sensor circuit, Carbon buildup in the EGR system. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means
P0406 indicates Exhaust Gas Recirculation Sensor 'A' Circuit High.
Common causes
Common causes include Faulty EGR sensor 'A', Wiring issues or a poor connection in the sensor circuit, Carbon buildup in the EGR system.
Severity
Moderate - service should be scheduled soon.
Can I drive?
The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.
What is this?
Table of contents Created and updated by William Orellana on Aug 18, 2024
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Code P0406 Description

The P0406 diagnostic trouble code indicates a problem with the Exhaust Gas Recirculation (EGR) sensor 'A' circuit on the vehicle. The EGR system is responsible for recirculating a portion of the exhaust gases back into the engine's intake manifold to reduce emissions and control combustion temperatures. The EGR sensor 'A' is a crucial component that monitors the EGR system's operation and provides feedback to the vehicle's engine control module (ECM). When the sensor detects that the voltage in the circuit is too high, it triggers the P0406 code.

OBDII Code P0406 - Exhaust Gas Recirculation Sensor 'A' Circuit High
P0406 Code - Exhaust Gas Recirculation Sensor 'A' Circuit High

Common Causes of P0406

  1. Faulty EGR sensor 'A'
  2. Wiring issues or a poor connection in the sensor circuit
  3. Carbon buildup in the EGR system
  4. ECM software or hardware issues
  5. Vacuum leaks in the EGR system

Symptoms of P0406

  1. Check Engine Light illuminated on the dashboard
  2. Reduced engine performance
  3. Rough idling or stalling
  4. Increased fuel consumption
  5. Failed emissions test

How to Fix P0406

  1. Diagnose the issue using a scan tool to confirm the P0406 code and pinpoint the exact cause.
  2. Inspect the wiring and connections in the EGR sensor 'A' circuit for any damage or corrosion.
  3. Test the EGR sensor 'A' for proper voltage and resistance values, replacing it if necessary.
  4. Clean out any carbon deposits in the EGR system and ensure proper operation of the EGR valve.
  5. Clear the code from the ECM's memory and perform a test drive to verify that the issue has been resolved.

Cost to Fix P0406

The typical repair costs for resolving a P0406 code can range from $100 to $300, depending on the extent of the issue and the specific components that need to be replaced. This estimate includes the cost of parts such as a new EGR sensor 'A' and any labor charges incurred during the repair process. It's important to note that actual repair costs can vary based on the vehicle's make and model, as well as the shop's hourly labor rates.

When is the Code Detected?

An improper voltage signal is sent to ECM through the valve

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Code P0406 Information for Specific Makes

  • P0406 Acura — Exhaust Gas Recirculation Valve Position Sensor Circuit High Voltage
  • P0406 Buick — Exhaust Gas Recirculation Position Sensor Circuit High Voltage
  • P0406 Cadillac — Exhaust Gas Recirculation Position Sensor Circuit High Voltage
  • P0406 Chevrolet — Exhaust Gas Recirculation Position Sensor Circuit High Voltage
  • P0406 Chrysler — Exhaust Gas Recirculation Position Sensor Circuit High
  • P0406 Dodge — Exhaust Gas Recirculation Position Sensor Circuit High
  • P0406 Ford — Exhaust Gas Recirculation Sensor 'A' Circuit High
  • P0406 GMC — Exhaust Gas Recirculation Position Sensor Circuit High Voltage
  • P0406 Honda — Exhaust Gas Recirculation Valve Position Sensor Circuit High Voltage
  • P0406 Infiniti — Exhaust Gas Recirculation Temperature Sensor Circuit High Input
  • P0406 Isuzu — Exhaust Gas Recirculation Position Sensor Circuit High Voltage
  • P0406 Jeep — Exhaust Gas Recirculation Position Sensor Circuit High
  • P0406 Lincoln — Exhaust Gas Recirculation Sensor 'A' Circuit High
  • P0406 Mazda — Exhaust Gas Recirculation Sensor 'A' Circuit High
  • P0406 Mercedes-Benz — Exhaust Gas Recirculation Sensor 'A' Circuit High
  • P0406 Mercury — Exhaust Gas Recirculation Sensor 'A' Circuit High
  • P0406 Mitsubishi — Exhaust Gas Recirculation Position Sensor Circuit High
  • P0406 Nissan — Exhaust Gas Recirculation Temperature Sensor Circuit High Input
  • P0406 Pontiac — Exhaust Gas Recirculation Position Sensor Circuit High Voltage
  • P0406 Saturn — Exhaust Gas Recirculation Position Sensor Circuit High Voltage
About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

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