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Engine-Codes – Generic – P0402

P0402 Code - Exhaust Gas Recirculation Flow Excessive Detected

Quick Answer

The P0402 code indicates that the Exhaust Gas Recirculation (EGR) flow is excessive, meaning that there is an issue with the amount of exhaust gas being recirculated back into the engine. Common causes include Clogged EGR valve: A common cause of excessive EGR flow is a clogged or stuck EGR valve, preventing it from functioning properly, Faulty EGR solenoid: The EGR solenoid controls the flow of exhaust gas into the intake manifold, and if it malfunctions, it can lead to excessive EGR flow, Carbon buildup: Over time, carbon deposits can accumulate in the EGR system, obstructing the flow of exhaust gas and causing the system to malfunction. 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
P0402 indicates Exhaust Gas Recirculation Flow Excessive Detected.
Common causes
Common causes include Clogged EGR valve: A common cause of excessive EGR flow is a clogged or stuck EGR valve, preventing it from functioning properly, Faulty EGR solenoid: The EGR solenoid controls the flow of exhaust gas into the intake manifold, and if it malfunctions, it can lead to excessive EGR flow, Carbon buildup: Over time, carbon deposits can accumulate in the EGR system, obstructing the flow of exhaust gas and causing the system to malfunction.
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 11, 2024
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Code P0402 Description

The P0402 code indicates that the Exhaust Gas Recirculation (EGR) flow is excessive, meaning that there is an issue with the amount of exhaust gas being recirculated back into the engine. The EGR system plays a crucial role in reducing nitrogen oxide emissions by recirculating a portion of the engine's exhaust gas back into the intake manifold, lowering combustion temperatures and reducing harmful emissions. However, when the EGR flow is excessive, it can negatively impact the engine's performance and emissions output.

OBDII Code P0402 - Exhaust Gas Recirculation Flow Excessive Detected
P0402 Code - Exhaust Gas Recirculation Flow Excessive Detected

Common Causes of P0402

  1. Clogged EGR valve: A common cause of excessive EGR flow is a clogged or stuck EGR valve, preventing it from functioning properly.
  2. Faulty EGR solenoid: The EGR solenoid controls the flow of exhaust gas into the intake manifold, and if it malfunctions, it can lead to excessive EGR flow.
  3. Carbon buildup: Over time, carbon deposits can accumulate in the EGR system, obstructing the flow of exhaust gas and causing the system to malfunction.
  4. EGR vacuum hose leaks: Any leaks or damage to the vacuum hoses connected to the EGR system can result in excessive EGR flow.
  5. EGR temperature sensor malfunction: If the EGR temperature sensor is faulty or sending incorrect signals, it can cause the EGR system to operate improperly.

Symptoms of P0402

  1. Check engine light is illuminated
  2. Reduced fuel efficiency
  3. Rough idling or stalling
  4. Engine knocking or pinging
  5. Reduced engine performance

How to Fix P0402

  1. Diagnose the issue: Use an OBD-II scanner to retrieve the P0402 code and conduct a visual inspection of the EGR system components to identify the root cause of the problem.
  2. Clean or replace EGR valve: Remove and inspect the EGR valve for any carbon buildup or damage. Clean the valve or replace it if necessary.
  3. Check EGR solenoid: Test the EGR solenoid to ensure it is functioning properly. Replace it if it is faulty.
  4. Inspect vacuum hoses: Check all vacuum hoses connected to the EGR system for leaks or damage. Replace any faulty hoses.
  5. Test EGR temperature sensor: Verify the operation of the EGR temperature sensor using a multimeter. Replace the sensor if it is malfunctioning.

Cost to Fix P0402

The cost of repairing a P0402 code can vary depending on the specific cause of the issue and the vehicle's make and model. On average, the cost of parts for this repair can range from $100 to $400, with labor costs adding an additional $100 to $200. Overall, the total repair cost for addressing an excessive EGR flow issue typically falls in the range of $200 to $600. It is important to note that the actual cost may be higher or lower based on the factors mentioned earlier, and it is recommended to obtain quotes from local auto repair shops for a more accurate estimate.

When is the Code Detected?

High Exhaust Gas Recirculation (EGR) flow control is detected

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Code P0402 Information for Specific Makes

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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