EGR P0404 code accelerating. 2005 Buick Terraza

My Terraza has a 3.51 and I got the p0404 Exhaust Gas Recirculation EGR code. I get very poor gas mileage and it’s really slow and stumbles when accelerating up hills. I thought about this and decided to replace the EGR valve with a Delphi EGR. But I still had the same problem. Do I need to reprogram the Powertrain Control Module (PCM)? My Actron scan tool lists reprogramming the PCM as the number one fix for this code. But instead of that I replaced the EGR and still have the same problem. Do you know what the deal is here? Any help is welcome.
Experienced mechanics share their insights in answering this question :
For this code, there is a related technical service bulletin 06-06-04-003D dated March 20,2007. The TSB calls for installing a new EGR kit consisting of a new valve, tube, and wire connector, and directions to reprogram the powertrain control module. Just installing the valve is not a complete fix and reprogramming is needed. If you need further help with this, get in touch with a local dealer to see if this repair is covered.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

The EGR valve is located in the engine compartment (underneath the hood).
P0404 is an OBD-II generic code that the engine control module (ECM) detected the engine exhaust gas recirculation (EGR) valve or sensor is out of specification range or its performance has gone out of specification parameters.
The EGR position sensor detects the movement and position of the exhaust gas recirculation (EGR) valve pintle. The EGR pressure sensor detects exhaust gas flow through the EGR passage.
A faulty EGR valve can cause problems with the flow and operation of the EGR system leading to performance issues including a reduction in power, reduced acceleration and decreased fuel efficiency. It can also cause vehicle emissions to increase.
What Does Code P0404 Mean? Issue Severity: MODERATE – Extended driving with this code may cause internal engine damage. Repair Urgency: Get this code fixed as soon as possible.
The EGR valve is usually located near or attached to the intake manifold, with a tube running to the exhaust manifold. There should also be a vacuum or electrical connector (or both) running to the valve which will need to be detached.
The EGR valve is located in the engine compartment (underneath the hood).
The EGR Valve is one of the vital components of your vehicle`s engine. EGR stands for exhaust gas recirculation. Therefore, the valve is a type of emissions-control device that is located between the exhaust manifold and the intake manifold. This is normally closed by the time you turn on the engine.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

EGR P0404 code accelerating. 2005 Buick Terraza
ANSWER : For this code, there is a related technical service bulletin 06-06-04-003D dated March 20,2007. The TSB calls for installing a new EGR kit consisting of a new valve, tube, and wire connector, and directions to reprogram the powertrain control module. Just installing the valve is not a complete fix and reprogramming is needed. If you need further help with this, get in touch with a local dealer to see if this repair is covered.

EGR code, Cylinder 4 misfire code 0304 detected.
ANSWER : Hi there. The Exhaust Gas Recirculation (EGR) valve may be not designed for the emissions requirements for U.S. standards. If the EGR is pulling from cylinder number 4 and after replacing the EGR and the computer detects a misfire, then the EGR is malfunctioning and not responding. When you close off the tube to the EGR and the EGR light comes on and the misfire light goes out, then the EGR is not responding to your emissions system. I recommend replacing the EGR with the OEM specified part for the engine and all of the issues should go away. If you need further assistance with your misfire and EGR, then seek out a professional, such as one from Your Mechanic, to help you.

EGR code and Cylinder number 4 misfire detected.
ANSWER : Hi there. The Exhaust Gas Recirculation (EGR) valve may be the wrong one or the cheap design could be not designed for the emissions requirements for U.S. standards. If the EGR is pulling from cylinder number 4 and after replacing the EGR and the computer detects a misfire, then the EGR is wide open and not responsive. It is clearly the EGR as when you close off the tube that the EGR light comes on and the misfire light goes out. I recommend replacing the EGR with the OEM specified part for the engine and all of the issues should go away. If you need further assistance with your EGR and misfire, then seek out a professional, such as one from Your Mechanic, to help you.

I had a p0405 get code replaced egr valve, map sensor,mad sensor, and PCv valve just to be safe but still getting the code why?
ANSWER : The code P0405 and a rough idle is most likely due to carbon getting into the EGR pintle. This will hold the EGR open. When you are getting the rough idle you should shut off engine and remove EGR valve. Check to see if carbon is holding the pintle open. If it is then you will have to remove the carbon from the pintle. Then try and clean out the EGR passages by scrapping them using a round wire brush. Afterwards, start the engine for a few seconds with valve removed to blow out loose carbon. You should then spray a small amount of carbon cleaner into the passages to dissolve the carbon. Lastly, reinstall the EGR and reset the light and codes.

If you’d like assistance with this, consider YourMechanic, as a certified professional can come to the vehicles locations to perform these checks and properly diagnose your Check Engine Light.

1998 Mazda protege: Had the EGR valve replaced, cleared the computer codes, still get the check engine light then a EGR problem co
ANSWER : Code P0400 does not necessarily mean that there is something wrong with the EGR valve itself. The only way to condemn the EGR valve is to directly test it. In particular Code P0400 includes a circumstance where the EGR passages are simply blocked with carbon and thus little or no exhaust gases can flow into the intake manifold. Code P0400 also includes the possibility that the EGR valve is not opening due to no vacuum opening the valve from the EGR control solenoid. If the valve is electronically controlled, there could be a fault in the circuit. If your vehicle is equipped with an EGR temperature sensor, if the sensor is plugged with carbon, it can’t register a temperature change when the EGR valve is opened, signifying flow. The point is Code P0400 can never be interpreted as the EGR valve has failed. The only way to determine if an EGR valve has failed is to directly test the valve. To resolve this, that is perform a complete system diagnostic and find the root cause for the code having set, the recommended service is an EGR system diagnostic. If you request that service, the responding certified mechanic will get this fully resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

Engine is running rough and P0401, P0171 and P0174 codes.
ANSWER : The first thing to check is to see if the EGR solenoid will release the vacuum when the electrical connector is disconnected. If it still doesn’t release the vacuum then the solenoid should be replaced. The codes need to be cleared and the vehicle should be driven to see if any of the codes come back.

The EGR solenoid has a small foam filter on the vent side and it is there to keep dirt out of the valve. If dirt gets into it, the solenoid will be held open and allow vacuum to pass through it. If you find that the solenoid is not leaking vacuum when the connector is disconnected then you may have a problem with the DPFE telling the ECM to open the valve. From what it seems like, I think you will find the solenoid is going to be the problem. I’d recommend having a certified mechanic check your vehicle out, they will be able to properly diagnose your Check Engine Light codes and make the necessary repair.

I have a Code P0601 on the PCM. I replaced the PCM, and now I have a code P0118, code P0123, and code P0193.
ANSWER : Hi there, the short answer to your question is no . A PCM with a P0601 (which is a memory module error in the PCM) cannot reliably retrieve codes for the codes you list (P0118 – coolant temp sensor, P0123 – throttle position sensor, P0193 – fuel rail pressure sensor.

Most likely, the P0601 prevents the PCM from getting any codes from the engine sensors. The memory module error may cause in data corruption for collected sensor values, lose of data over multiple sampling periods, or failure of the data collection to work at all. Replacing the PCM was a necessary expense.

If you need assistance with the "new" codes, I would recommend having a Check Engine Light inspection completed by a mobile, professional mechanic, such as one from YourMechanic, to diagnose the new error codes and get an accurate assessment of the repairs needed.

New EGR Transducer Leads To Other Issues?
ANSWER : Hi there. Look to see where the EGR (Exhaust Gas Recirculation) is plumed into the engine. If the EGR is plumed into the cylinder number 3 and the EGR has a leak, then the cylinder number 3 will be weak and cause a misfire. If the EGR is plumed into the exhaust pipe, then the spark plug on the cylinder number 3 could have failed as the engine changed in temperature when replacing the EGR transducer. If you need further assistance with your engine misfire, then seek out a professional, such as one from Your Mechanic, to help you.