P0404 – Meaning, Causes, Symptoms, & Fixes

What Does Code P0404 Mean?

• P0404 definition: Exhaust Gas Recirculation Circuit Range/Performance
• Issue Severity: MODERATE – Extended driving with this code may cause internal engine damage.
• Repair Urgency: Get this code fixed as soon as possible.
• Diagnosis: 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.

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.

P0404 Causes

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

P0404 Symptoms

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

How Do I Fix Code P0404?

With a P0404 code, the first step is to get it properly diagnosed to figure out what is causing the malfunction related to the EGR system. Using the live data function of the FIXD sensor and app allows you to read and analyze engine data to properly diagnose a P0404 code.

If the sensors are all reading correctly and you’re not comfortable further diagnosing this issue at home, we recommend finding a RepairPal-certified shop to pinpoint the problem and give an accurate estimate for repairs.

These shops can not only help you figure out what’s going wrong before you waste time and money on the wrong parts, but they also offer a minimum 12-month, 12,000-mile warranty and stand behind all their estimates with guaranteed fair pricing.

> Find a RepairPal Certified Shop Near You

How Much Does It Cost to Fix Code P0404?

If you take your car to a shop for diagnosis, most shops will start with an hour of “diag time” (the time spent in labor diagnosing your specific issue). Depending on the shop’s labor rate, this typically costs somewhere between $75-$150. Many, if not most, shops will apply this diagnosis fee to any required repairs if you have them perform the repairs for you. From there, a shop will be able to give you an accurate estimate for repairs to fix your P0404 code.

Possible Repair Costs for P0404

When it comes to making repairs associated with the P0404 code, one or more of the below repairs may be needed to solve the underlying issue. For each possible repair, the estimated cost of repair includes the cost of the relevant parts and the cost of labor required to make the repair.

• EGR valve: $332 to $413

DIY Steps to Diagnose Code P0404

If you’d like to try to fix code P0404 at home without throwing money at parts, you’ll want to follow the steps below for proper diagnosis. Complete diagnosis may require some specialized equipment beyond what the FIXD Sensor can provide, but for the most part, this diagnosis and repair can be attempted by beginner DIYers.

DIY difficulty level: Beginner

This repair can be attempted by beginner DIYers.

Tools/parts needed (our top picks from Amazon):

• FIXD

STEP 1: USE FIXD TO ENSURE NO OTHER ENGINE CODES ARE PRESENT.

Scan your vehicle to verify P0404 is the only code present. If other codes are present, they must be addressed first.

STEP 2: CHECK FREEZE FRAME DATA.

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.

STEP 3: CHECK EGR VALVE.

Check the EGR valve to make sure there is no buildup of carbon that is preventing the valve from opening or closing. If there is a buildup of carbon, make sure to clean the valve in order to allow it to open and close properly.

STEP 4: CONSULT A PROFESSIONAL.

If at this point the vehicle is still setting the same code, you may have a more serious problem with your car’s oxygen sensor system, and you should bring the vehicle to a certified shop to have further diagnostic work performed.

Common P0404 Diagnosis Mistakes

Replacing the EGR valve or sensor before visually checking the wiring and the connection to the EGR position sensor.

Still Need Help Fixing Code P0404?

If you’ve followed the steps above and are still experiencing issues with the EGR valve system and code P0404, please contact the FIXD Mechanic Hotline if you’re a FIXD Premium subscriber or find a RepairPal certified shop near you to get the right repairs at a fair price.

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