P0404 Fault Code

Exhaust Gas Recirculation Circuit Range/Performance

• What does that mean?
• Symptoms
• Causes
• Solutions

The P0404 fault code indicates an issue with the Exhaust Gas Recirculation (EGR) circuit, specifically related to its range or performance. The EGR system is designed to recirculate a portion of the engine's exhaust back into the combustion chamber to lower emissions and improve fuel efficiency. When the EGR system isn't functioning correctly, it can lead to increased emissions and higher nitrogen oxide (NOx) levels.

What are the symptoms of the P0404 code?

Common symptoms associated with the P0404 code may include:

• Check Engine Light illuminated.
• Rough idle or stalling.
• Decreased engine performance or power.
• Increased emissions, leading to potential failed emissions tests.
• Knocking or pinging noise due to improper combustion.

What causes the P0404 code?

There are several potential causes for the P0404 code, including:

• A malfunctioning EGR valve that is stuck open or closed.
• Faulty wiring or connectors in the EGR circuit.
• A clogged EGR passage that restricts airflow.
• A failed EGR cooler or related components.
• Vacuum leaks affecting EGR operation.

How to fix P0404?

To resolve the P0404 code, the following steps are typically recommended:

• Inspect the EGR valve for proper operation and replace it if necessary.
• Check the wiring and connectors for any signs of damage or corrosion, and repair or replace as needed.
• Clean any clogged EGR passages to restore proper airflow.
• Test the EGR cooler and associated components for functionality and replace any faulty parts.
• Clear the fault codes and perform a road test to ensure the problem is resolved.