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Engine-Codes – Generic – P0405

P0405 Code - Exhaust Gas Recirculation Sensor 'A' Circuit Low

Quick Answer

The P0405 code indicates a problem with the Exhaust Gas Recirculation (EGR) sensor 'A' circuit being lower than the expected voltage range. Common causes include Faulty EGR Sensor: The EGR sensor itself may be faulty and not providing the expected voltage range to the ECM, Wiring or Connector Issues: Damage to the wiring or connectors in the EGR sensor circuit can prevent proper communication between the sensor and ECM, ECM Malfunction: A problem with the engine control module (ECM) could also be causing the low voltage reading from the EGR sensor. 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
P0405 indicates Exhaust Gas Recirculation Sensor 'A' Circuit Low.
Common causes
Common causes include Faulty EGR Sensor: The EGR sensor itself may be faulty and not providing the expected voltage range to the ECM, Wiring or Connector Issues: Damage to the wiring or connectors in the EGR sensor circuit can prevent proper communication between the sensor and ECM, ECM Malfunction: A problem with the engine control module (ECM) could also be causing the low voltage reading from the EGR sensor.
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 Sep 08, 2024
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Code P0405 Description

The P0405 code indicates a problem with the Exhaust Gas Recirculation (EGR) sensor 'A' circuit being lower than the expected voltage range. The EGR system is crucial for reducing emissions and improving fuel efficiency by recirculating a portion of the exhaust gases back into the engine cylinders. The EGR sensor monitors the EGR system's operation and sends feedback to the engine control module (ECM) to ensure proper emissions control.

OBDII Code P0405 - Exhaust Gas Recirculation Sensor 'A' Circuit Low
P0405 Code - Exhaust Gas Recirculation Sensor 'A' Circuit Low

Common Causes of P0405

  1. Faulty EGR Sensor: The EGR sensor itself may be faulty and not providing the expected voltage range to the ECM.
  2. Wiring or Connector Issues: Damage to the wiring or connectors in the EGR sensor circuit can prevent proper communication between the sensor and ECM.
  3. ECM Malfunction: A problem with the engine control module (ECM) could also be causing the low voltage reading from the EGR sensor.
  4. Carbon Build-Up: Excessive carbon build-up in the EGR system can also affect the sensor's operation and trigger the P0405 code.
  5. Vacuum Leaks: Any leaks in the vacuum system that controls the EGR system can disrupt its operation and lead to a low voltage reading.

Symptoms of P0405

  1. Check Engine Light: The most common symptom associated with the P0405 code is the illumination of the check engine light on the vehicle's dashboard.
  2. Decreased Fuel Efficiency: A malfunctioning EGR sensor can lead to decreased fuel efficiency as the engine may not be operating at optimal levels.
  3. Rough Idling: The engine may experience rough idling or hesitation when the EGR system is not functioning correctly.
  4. Increased Emissions: The vehicle may produce higher emissions than normal, leading to potential environmental concerns.
  5. Engine Misfires: In severe cases, the engine may experience misfires or stalling due to improper EGR system operation.

How to Fix P0405

  1. Diagnose the Issue: Use a scan tool to retrieve the P0405 code and perform a thorough inspection of the EGR system, sensor, wiring, and connectors to determine the root cause of the problem.
  2. Replace EGR Sensor: If the EGR sensor is found to be faulty, replace it with a new sensor following the manufacturer's guidelines.
  3. Repair Wiring or Connectors: If there are any damaged wires or connectors in the EGR sensor circuit, repair or replace them as needed.
  4. Clear Codes and Test Drive: After completing the repairs, clear the diagnostic trouble codes from the ECM's memory and test drive the vehicle to ensure the issue has been resolved.
  5. Perform Emissions Test: To verify that the vehicle is now operating within acceptable emissions levels, consider performing an emissions test after the repair process.

Cost to Fix P0405

The typical repair costs for addressing the P0405 code can vary depending on the specific cause of the issue and the vehicle's make and model. In general, replacing the EGR sensor can cost between $150 and $300, while repairing wiring or connectors may add additional labor costs. Overall, the total repair cost, including parts and labor, can range from $200 to $500. It is recommended to consult with a professional mechanic or auto repair shop to get a more accurate estimate based on the specific circumstances of the vehicle. Keep in mind that diagnosis time and labor rates at auto repair shops can vary based on location, vehicle type, and other factors.

When is the Code Detected?

An improper voltage signal is sent to ECM through the valve

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Code P0405 Information for Specific Makes

  • P0405 Buick — Exhaust Gas Recirculation Position Sensor Circuit Low Voltage
  • P0405 Cadillac — Exhaust Gas Recirculation Position Sensor Circuit Low Voltage
  • P0405 Chevrolet — Exhaust Gas Recirculation Position Sensor Circuit Low Voltage
  • P0405 Chrysler — Exhaust Gas Recirculation Position Sensor Circuit Low
  • P0405 Dodge — Exhaust Gas Recirculation Position Sensor Circuit Low
  • P0405 Ford — Exhaust Gas Recirculation Sensor 'A' Circuit Low
  • P0405 GMC — Exhaust Gas Recirculation Position Sensor Circuit Low Voltage
  • P0405 Infiniti — Exhaust Gas Recirculation Temperature Sensor Circuit Low Input
  • P0405 Isuzu — Exhaust Gas Recirculation Position Sensor Circuit Low Voltage
  • P0405 Jeep — Exhaust Gas Recirculation Position Sensor Circuit Low
  • P0405 Lincoln — Exhaust Gas Recirculation Sensor 'A' Circuit Low
  • P0405 Mazda — Exhaust Gas Recirculation Sensor 'A' Circuit Low
  • P0405 Mercedes-Benz — Exhaust Gas Recirculation Sensor 'A' Circuit Low
  • P0405 Mercury — Exhaust Gas Recirculation Sensor 'A' Circuit Low
  • P0405 Mitsubishi — Exhaust Gas Recirculation Position Sensor Circuit Low
  • P0405 Nissan — Exhaust Gas Recirculation Temperature Sensor Circuit Low Input
  • P0405 Pontiac — Exhaust Gas Recirculation Position Sensor Circuit Low Voltage
  • P0405 Saturn — Exhaust Gas Recirculation Position Sensor Circuit Low 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.

Frequently Asked Questions about P0405 Code

1. What are the common symptoms of OBDII code P0405 (Exhaust Gas Recirculation Sensor 'A' Circuit Low)?

- Common symptoms include rough idling, engine hesitation, decreased fuel efficiency, and the illumination of the Check Engine Light.

2. What are the possible causes of OBDII code P0405?

- The code P0405 can be caused by a faulty EGR sensor, damaged wiring or connectors in the EGR system, or a problem with the EGR valve itself.

3. How can I diagnose the cause of OBDII code P0405?

- Diagnosing the issue involves checking the EGR sensor for proper voltage, inspecting the wiring for any damage, and testing the EGR valve for functionality using a multimeter.

4. Can a dirty EGR system cause code P0405?

- Yes, a dirty or clogged EGR system can cause insufficient flow and trigger code P0405. Regular maintenance and cleaning of the EGR system can help prevent this issue.

5. What are the potential risks of ignoring OBDII code P0405?

- Ignoring code P0405 can lead to poor engine performance, increased emissions, and potential damage to other engine components over time.

6. How can I repair OBDII code P0405 at home?

- Home repair options include cleaning the EGR valve, checking and cleaning the EGR passages, and inspecting the wiring and connections for any visible issues.

7. Is it safe to drive with OBDII code P0405 present?

- It is generally safe to drive with code P0405, but it is recommended to address the issue promptly to prevent further damage and ensure optimal engine performance.

8. Can code P0405 be triggered by a loose gas cap?

- No, code P0405 specifically relates to the Exhaust Gas Recirculation system and is not related to issues with the gas cap.

9. Will resetting the Check Engine Light resolve code P0405?

- Resetting the Check Engine Light may temporarily turn off the warning, but if the underlying issue causing code P0405 is not addressed, the light is likely to come back on.

10. How can a mechanic further diagnose and repair OBDII code P0405?

- A mechanic may use specialized diagnostic tools to pinpoint the exact cause of the issue, perform thorough testing of the EGR system components, and replace any faulty parts as needed.

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