Fix P0404: Mechanic’s solutions that WORKED

The code P0404: Exhaust Gas Recirculation “A” Control Range/Performance points to potential issues with your vehicle’s Exhaust Gas Recirculation (EGR) system, often related to the EGR valve, EGR pressure sensor, vacuum system, or software problems.

P0404 quick overview

Meaning	P0404 – Exhaust Gas Recirculation “A” Control Range/Performance
Is it serious?	While not an immediate emergency, it should be addressed to prevent potential engine performance issues and emissions problems.
Possible causes	– EGR valve malfunction or carbon buildup. – EGR pressure sensor issues. – Vacuum system problems. – Faulty MAP (Manifold Absolute Pressure) sensor. – Clogged EGR cooler. – Software or calibration issues.
How to diagnose?	1. Use a diagnostic scan tool to retrieve the trouble codes and freeze frame data. 2. Visually inspect the EGR valve and associated components for physical damage or carbon buildup. 3. Test the EGR pressure sensor for proper functioning. 4. Check the vacuum system for leaks or blockages. 5. Inspect the MAP sensor and its connections. 6. Perform an EGR system cleaning if carbon buildup is present. 7. Ensure the software and calibration are up to date. 8. Road test the vehicle to confirm the issue has been resolved after repairs.
What is EGR valve?	An EGR (Exhaust Gas Recirculation) valve is a component in a vehicle’s engine that recirculates a portion of exhaust gases back into the engine’s combustion chamber to reduce emissions and control combustion temperature.

How to fix P0404 – learn from mechanics

I looked into P0404 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Chevrolet

1. Vehicle Information:

• 1999 Chevrolet Cavalier 2.2L
  

2. Issue + Repair History:

• Issue: MIL (Check Engine Light) on
• Repair History: The technician pulled codes and found codes P0405 (EGR Recirculation Sensor A Circuit) and P0404 (EGR Recirculation circuit low). No EGR system was present on this vehicle.
  

3. Other OBD2 Codes + Test Results:

• No other OBD2 codes or test results were mentioned.
  

4. Suggestions to Fix Issue (Community Recommendations):

• The technician received suggestions to recheck the code numbers as P0405 and P0404 were not codes for this car.
• Use a different brand scan tool to verify the codes and interpret the information correctly.
• Consider the possibility that the engine may have been changed, and the original unit had an EGR system. In such cases, installing EGR system hardware or programming the PCM with a non-EGR VIN number might be necessary.
  

5. Final Fix:

• The technician opted to use a different ECM (engine control module) or PCM (powertrain control module) with the same part number (16228016) to address the issue. After performing this replacement, the vehicle was successfully started and driven, and it passed an emissions test

Case #2: Buick

1. Vehicle Information:

• 2001 Buick Park Avenue 3.8L
  

2. Issue + Repair History:

• Issue: Customer brought the vehicle with a steady SES (Service Engine Soon) light, which had turned on immediately when she started the car in the garage.
• Repair History: The technician checked for trouble codes and found codes P0440 (Evap System) and P0404 (EGR open position performance). The customer had previously taken a 400-mile trip without the light coming on.
  

3. Other OBD2 Codes + Test Results:

• No other OBD2 codes or test results were mentioned.
  

4. Suggestions to Fix Issue (Community Recommendations):

• Check for vacuum leaks, especially around the EVAP components.
• Use a scan tool with a service bay test mode to verify if there is an EVAP leak present.
• Check for a reflash update from the dealer.
• Inspect the gas cap for defects or improper tightening.
• Examine the EGR valve for carbon buildup or sticking and perform a decarbonization cleaning if needed.
• Test the purge valve for leaks or being stuck open.
• Inspect the fuel tank sending unit seal.
  

5. Final Fix:

• The technician replaced the EGR valve and the purge solenoid. The customer reported that the SES light had not come on after driving the vehicle for a week.

Case #3: Chrysler

1. Vehicle Information:

• 2005 Chrysler Pacifica Touring 3.5L
  

2. Issue + Repair History:

• Issue: Initially came in with code P0406 (EGR position sensor circuit high). Replaced the EGR valve with an aftermarket unit. Now getting code P0404 (EGR position sensor performance).
• Repair History: Replaced the EGR valve twice.
  

3. Other OBD2 Codes + Test Results:

• No other OBD2 codes or test results were mentioned.
  

4. Suggestions to Fix Issue (Community Recommendations):

• Use only Mopar (OEM) parts for the EGR valve.
• Check the grounds on the left frame rail below the battery, particularly the grounds with multiple wires on each stud. Ensure they are in good condition.
• Check the readings from the EGR position sensor.
• Disconnect the battery to reset the PCM after installing the OEM EGR valve.
  

5. Final Fix:

• The technician installed an OEM Mopar EGR valve, and the customer confirmed that the SES light had stayed off. Aftermarket EGR valves were suspected to be the issue, and the problem was resolved with the OEM part.

Case #4: Dodge

1. Vehicle Information:

• 2005 Dodge Sprinter 2500 2.7L
  

2. Issue + Repair History:

• Issue: Complaint of transmission slipping, but after a road test, it was determined that the engine struggled to rev over 3000 rpm. Fuel filter replaced, and exhaust system disconnected with no improvement.
• Repair History: Replaced fuel filter, attempted running with no exhaust.
  

3. Other OBD2 Codes + Test Results:

• P0404 – EGR
  

4. Suggestions to Fix Issue (Community Recommendations):

• Replace the MAF (Mass Air Flow) sensor.
• Clean the EGR (Exhaust Gas Recirculation) valve.
• Check for trash buildup on the intake muffler.
• Check the turbo boost helper pump in the fuel tank.
• Inspect the EGR valve for proper closing.
• Verify the EGR valve operation and ensure it closes fully.
  

5. Final Fix:

• After removing the EGR valve for inspection, broken green plastic pieces were found inside. The EGR valve was replaced with a new one, and the codes were cleared at the dealer. The problem was resolved, and the vehicle regained its power.

Case #5: GMC

1. Vehicle Information:

• 2004 GMC Sierra 2500 HD 6.6L
  

2. Issue + Repair History:

• Issue: MIL (Malfunction Indicator Lamp) on with code P0404 (EGR-related issue) even after replacing the EGR vacuum pump.
• Repair History: Replaced EGR vacuum pump.
  

3. Other OBD2 Codes + Test Results:

• P0404 – Exhaust Gas Recirculation “A” Control Range/Performance
  

4. Suggestions to Fix Issue (Community Recommendations):

• Inspect and possibly replace the EGR valve.
• Check the EGR pressure sensor.
• Investigate the vacuum sensor, MAP sensor, and ports for blockages.
• Perform a diagnostic procedure to pinpoint the problem.
• Consider performing a software update as per GM bulletin for EGR issues.
• Ensure the EGR cooler is not clogged.
• Use an OE (Original Equipment) air filter.
• Clean the MAF (Mass Air Flow) sensor.
  

5. Final Fix:

• The EGR valve was replaced along with other items mentioned in the discussion.
• After road testing for over 20 miles, the MIL (Malfunction Indicator Lamp) remained off, indicating a successful fix.