P0404 – Meaning, Causes, Symptoms, & Fixes
Code P0404 Definition
Exhaust Gas Recirculation Circuit Range/Performance
What Does P0404 Mean
Your car has an Exhaust Gas Recirculation (EGR) System, whose primary function is to redirect exhaust back into your vehicle’s cylinders in order to lower cylinder temperatures and nitrogen oxide emissions. In order to know if your EGR’s valve is operating properly, the EGR valve’s feedback system communicates with your Power Control Module (PCM) to let it know if your valve is open, closed, or partially closed at any given time. When P0404 is triggered, it means that the PCM has been told that the valve is performing in a way that is outside of its specified parameters. More specifically, the PCM has been told that the valve is closed when it should be open, or vice-versa.
Code P0404 Symptoms
- Check engine light
- Pinging on acceleration
- Engine may run rough
- High nitrogen oxide emissions
- Possible Stalling
Code P0404 Causes
- Faulty EGR valve
- Faulty EGR sensor
- EGR sensor wiring/connector problems
- EGR valve movement isn’t smooth
- Carbon buildup in EGR valve
Code P0404 Severity- Moderate
Although a car owner could go a significant period of time without noticing some of the symptoms of code P0404, it is important that the issue is fixed as soon as possible. A faulty EGR valve could lead to serious engine problems in the long run, and an increase of nitrogen oxide emissions.
Code P0404 Common Diagnosis Mistakes
Replacing the EGR valve or sensor before visually checking the wiring and the connection to the EGR position sensor.
- Tools Needed to Diagnose:
Difficulty of Diagnosis and Repair-(3-7)
- You will need a scanner tool for this next action, and the FIXD scanner is perfect for it! Scan and document the codes in order to verify that the problem exists.
- Often times code P0404 does not actually indicate that there is something wrong with the EGR valve itself, but actually that the EGR sensor is telling your PCM that the proper amount of EGR needed to flow back into your cylinders and cool them is not present.
- Make sure to pay careful attention to the freeze frame data associated with the code to determine what engine conditions were present at the time the code was triggered. This can give you a better indication of which part of the combustion process is not functioning properly.
- Check the EGR valve to make sure there is no build up of carbon that is preventing the valve from opening or closing.
- If there is a build up of carbon, make sure to clean the valve in order to allow it to open and close properly
- Repair any wiring that is associated with the EGR valve or position sensor that could be causing the valve not to open or close properly.
- Replace EGR valve or position sensor if it is determined that they cannot operate properly.