EGR valve code keeps coming back

There are a number of things that can cause any one code so we need to start with the actual code. Can you provide the actual code and then we can figure out next steps? Thanks

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Okay. That is great. Thanks for the update. We will be here when you get to it. Thanks

Okay. That helps. Can you confirm that your vehicle has the EGR module and not just a valve? The fact that you have 6 wires I am sure you do but I need you to look at the connector and tell me what these wires have for voltage. I understand you said top left but I am not sure if you had it plugged in or which way you were looking at it so can we match up the wires and tell me what pin 1-6 had according to this connector view?

Once we get this, I will run through the testing and let you know if we have another issue or provide more guidance. Plus I will know which testing to send over once we get this info.

Okay. We have some digging to do with this because some of those don't sounds correct namely the 9.4 volts. However, pin 4 cannot be 0 so we need to start there. Fuse 21 in the battery junction box is what we need to check and go from there. Let me know if this fuse is okay and if it is we are going to need to jump 12 volts to this pin and retest the operation.

Just to clarify, you jumped 12 volts to the EGR module or you put 12 volts to the connector with it unplugged? That circuit is the voltage supply circuit that is a 12 volt supply from fuse 21 in the battery junction box.

If you put 12 volts to the EGR module and it almost burned up the wire then that may be the issue. You need 12 volts on that wire so if your jumper almost melted then that wire from the fuse may have melted as well. A short to ground will cause the wire to melt.

As you can see in the wiring diagram that fuse splices off and feeds other things as well. So we need to check for a short to ground on that wire and the EGR. You do that by unhooking the connector and put your meter on continuity or ohms and then put one lead on that pin and the other on the negative battery terminal. It should be an open circuit or the meter should say OL.

We need to make sure we are in the correct cavity of the connector. There is no question that there needs to be 12 volts on terminal 4 as it is labeled as the power wire. When you are looking at the diagram below this is showing the connector disconnected. So you are looking at the inside of the connector and then number 4 should on the lower right corner. If you are looking at this from the back side of the connector, you would actually be looking at number 6 in the lower right corner which would be a grey/red wire. I think you jumped 12 volts to the signal return which is a 5 volt reference circuit and would make sense why the wire got hot.

Can you get a picture of the connector as you are looking at it? I think that is why we are not on the same page.

Once we straighten that out, we need to find out why we don't have 12 volts on pin 4 so we need to test for a short to power and ground.

Okay. Glad we got that figured out. Here is the testing for these codes. It is lengthy but will take us through to the solution.

I have seen this problem I would remove the EGR valve and check the ports leading up to and going into the intake manifold I have seen them clog up which causes this issue. An easy way to do this is too remove the EGR and start the car, it should be loud then stall quickly if the passages are open. Here is how to remove the intake to be hot tanked or replaced if this is the problem. Check out the diagrams (below). Please let us know what you find. We are interested to see what it is.

Sorry if that did not help. Unfortunately we have no way of knowing what your level of expertise is so we can only supply the information and answer the questions as best as possible. Unfortunately not all vehicle issues are as simple as putting a part on it and do require diagnostic work to figure it out.

So let's walk through this testing to see if we can figure something out. Your codes are 0402 and 0403. As you can see on step one that sends you to HH12 for the P0402 and HH 22 for P0403.

Let's start with HH12.

HH12 tells you to disconnect the EGR module (ESM) and check voltage on pin 2. Based on what you said it was 4.9v. It then asks you if it is between 4.5-5.5v. The answer is yes so you go to HH13.

HH13 says to monitor the data in the PCM with a scan tool. If you don't have that then you can monitor the voltage on the DPFE and get the same info. You will need a vacuum gauge/hand pump so that you can pull it into a 8-9 inch of mercury vacuum as it asks. Let's say it passes that and you move to HH14. If it did not then you replace the DPFE.

HH14 asks you to check for a blockage in the EGR regulator solenoid. Again, you need the vacuum hand pump again to pull it into a 10-15 in-hg vacuum. If this does not bleed off then you need a new EGR vacuum regulator solenoid. Let's say that passed and you move onto HH15.

HH15 is asking you to inspect the EGR valve for carbon build up. If you find it, you can clean it or replace it. If there is none then the issue is not currently present.

For P0403 you start at HH22. This is asking you to check the operation of the EGR by using a scan tool. You don't have one so let's assume it does not stall when you perform this test because if it does then the issue is not present at this time so let's assume it is currently broken so it would answer this question as "No" and you go to HH23.

HH23 is asking you to check voltage from the EGR module (ESM) for voltage and based on your reading of 12 volts, you would answer yes that it is greater then 10v. Go to HH24

HH24 needs you to check the EGR coil and you do this by disconnecting the connector and measure resistance between pin 4 and pin 1. What is the resistance reading? Is it between 26-40 ohms? If it is not then you replace the EGR vacuum regulator solenoid. Let's assume it is and you go to HH25

HH25 is asking you to check the harness for an open circuit. You need to disconnect the EGR Solenoid and the PCM and check resistance on that wire. The chart shows where to put your leads but basically you need to be on both ends of the wire. Let's assume it is less then 5 ohms. If not you have an open or high resistance and need to repair that wire.

HH26 is asking to check the harness for a short to voltage. Put the leads as it says in the chart. Repair the wire if there is more the 1 volt on it.

HH27 is asking to test for a short to ground. Again put your leads where it asks and do you have more then 10k ohms of resistance? If yes, then you have no continuity to ground which is good. If you do then you need to repair that wire. Proceed to HH29 if it passed.

HH29 is telling you to inspect the PCM for any visual issues like corrosion or pin/terminal issues. If not, put a PCM in it.

So this means you could just replace these parts and if that does not fix it you will need to replace the wiring harness.

1. DPFE
2. EGR regulator solenoid
3. ESM
4. PCM
5. Wiring issue

Again, based on these codes I cannot just tell you what parts to replace. We must go through this testing in order to figure out what to do or your guess is as good as mine. Hopefully this helps.

As I said in my response, ESM means EGR System Module. It is the assembly that you showed prior and what I attached below. Also, DPFE is part of this assembly and detailed in the attachment. So if you replaced this years ago and just replaced it again and the codes are still there, then we have one of the other issues.

I understand it is frustrating that I can't just tell you what to replace but unfortunately we need to go through the testing to know for sure what the issue is. Otherwise we can just start replacing parts and hope one of them fixes it. This gets expensive and even more frustrating. You are attempting to perform pretty heavy diagnostic work and I understand you are not a mechanic but that is just going to complicate things as there is not a basic level of understanding that is needed to do this heavy of diagnostic work.

However, let's try to simply this, if you have replaced the ESM and the codes are still there, I suspect the P0403 is the cause of this. Take a look at the third attachment. This lists the possible causes of this code. As you can see it is saying the wiring is the issue or the EGR solenoid, which is part of what you replaced, and finally a PCM (Powertrain Control Module).

This means we need to perform the wiring testing that I attached in those documents and spelled out in my response.

So we need to start at HH 22. Let's assume it passed. Go to HH23. Your reading you told me for that was 12 volts. That passes so we go to HH24. You need to take this reading. Take a look at attachment 4 of this post. You need to measure resistance between pin 1 and 4 of the connector of the ESM. So disconnect that connector and use the diagram of the connector (attachment 5) to check the resistance. What is this number from your meter?

Once we know the result here we can take the next step.

Sounds like you have more then enough ability to do this. Let's just go step by step and based on the results we will get it figured out. Let me know the resistance whenever you can and we will go from there. Thanks