Auxiliary Emissions ControlOBD2 Codes

P0404 – Meaning, Causes, Symptoms, & Fixes

Reading Time: 2 minutes


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.

What Are the Symptoms of Code P0404?

  • Check engine light
  • Pinging on acceleration
  • Engine may run rough
  • High nitrogen oxide emissions
  • Possible Stalling

What Causes Code P0404?

  • Faulty EGR valve
  • Faulty EGR sensor
  • EGR sensor wiring/connector problems
  • EGR valve movement isn’t smooth
  • Carbon buildup in EGR valve

How Serious Is Code P0404? – 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.

P0137 Diagnosis and Repair:

  • Tools Needed to Diagnose:

Difficulty of Diagnosis and Repair-(3-7)

  1. 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.
  2. 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.
  3. 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
  4. 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.
  5. Replace EGR valve or position sensor if it is determined that they cannot operate properly.


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  1. The car is a 2006 Chrysler 300 touring. I was getting the code p0406. I changed the EGR valve to a new egr valve. It was carbon buildup in the egr valve and egr valve tube. I also changed the spark plugs. I noticed the one ignition coil was in bad shape but I still used the ignition coil. Once I was done, I drove the car to around 65 miles to have the sensors and everything read. The check engine light came on, it was p0404 and p0300. I noticed the hesitation of idle and misfires. I knew it had to be that bad ignition coil. I’m wondering if that would also bring up that p0404 code. If because of the bad ignition coil, that would affect the egr valve position sensor from working correctly? I bought a new ignition coil. I hope that helps fix the problem with hesitation and with the egr valve position sensor.

    1. Did it work ?

      1. I’m wondering too if changing the coil worked?!

    2. I have a 2006 Chrysler 300 also. Also had 0406 code and 0403 code. Change egr, solenoid, plugs, map sensor, took to garage to finally get light off. Went on trip days after getting the car back. Before we drove 450 miles the light came back on now it’s the 0404 code. Ugh! What can this be?

  2. I have a problem with my 2000 bravada ( failed emissions test ) I changed the EGR valve and MAP sensor and the check engine light still came on. I’m kind of stuck and don’t know what way to go, can you help please?

  3. have a 2005 buick lesabre3.8 had codes po172 running too rich po128 temp (replaced) po404 po420. have hesitation like its loading up ir running too rich. im planning to swap egr next . do i need to reset ecm after replacing ( unhook batterery to reset system?

  4. will CLR clean egr valve ,on 01, 3.5 intrepid cannot see much to clean,wonder if soaking in CLR will work??

    1. I thought I could try that to. Too many hard to reach places in EGR valve to get out all the carbon

  5. the code on my 2008modyssey came on after the alternator was replaced. The alternator light came on after a huge rainstorm. Since the alternator was replaced by my husband, the car idles a bit rough and the orange light came on. The reader says P0404

    1. Did you find the fault?

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