2002 Buick Park Avenue EGR Valve Replaced Error P1404 Keeps Coming Back

I am $500 into mechanics fees. They have so far replaced the EGR valve and updated the onboard computer. I cannot spend too much more money of the issue.

I have reset the onboard computer in this car by disconnecting the battery. The code continues to come back.

I have communicated with Scanner Dan via YouTube video He has asked me what the EVP voltage is and that I need a voltmeter to perform the measurement. I have a voltmeter but do not yet know how to perform the measurement.

Hey patricktoday! For our reference, this is the EGR circuit on your Park Avenue:



You'll want to take three measurements. All measurements should be taken with the key on but engine off, EGR connector plugged in and backprobed, with the multimeter ground on the batter negative post.

1.) Voltage on the grey wire, pin D.
2.) Voltage on the brown wire, pin C.
3.) Voltage on the black wire, pin B.

Let us know what your results are and we'll discuss the next step.

I placed three light blue dots on the wires that were back probed (see picture below)

From left to right the voltages are as follows:

Pin B Black 48.4 mV
Pin C Brown .744 V
Pin D Grey 5.07 V (when I had put everything away and went back into the house I noticed there are 2 grey wires. Did I measure the correct one?)

Yep, you got the right wires. No worries there.

.74V on the EGR position signal is fine with the valve closed. The signal ground and the 5V reference are good, too. How often, and under what conditions, does this code reset? This is the code set criteria for P1404:



If you were to turn the key on, clear codes and start the engine, would the code reset after 80 seconds?

Tyler,

Thank you for your reply!

Way more than 80 seconds and random. For instance, in the three times I have reset the code these were the approximate miles on the trip meter:

1) 20 miles
2) 60 miles
3) 7 miles

The car seems to run fine. My concern is that down the road something else will go out on the car and I will not be aware because the service light is on.
The Service Engine Soon light is on now BTW I simply gave up resetting it for the moment. How do you suggest I proceed from here?

patricktoday wrote:

Way more than 80 seconds and random. For instance, in the three times I have reset the code these were the approximate miles on the trip meter:

1) 20 miles
2) 60 miles
3) 7 miles

Gotcha.

The intermittent nature of the problem may make this one tough to catch in the act. Unfortunately, scan data really would be valuable in being able to compare EGR position to the learned EGR closed position on a test drive. I know that you already did a battery disconnect, but that doesn't mean the reset actually took.

Is there any noticeable lack of power on hard acceleration? I have seen plugged catalytic converters cause enough backpressure to hold the EGR valve pintle off its seat and cause this code.

I can do the battery reset again. How long do I need to leave it disconnected for?

There is no problem with power the accelerator is pushed down that I have noticed. How can I know for sure if the convertor is or is not clogged up?

I am open to purchasing a scanner to resolve this problem. Unfortunately, I cannot afford to spend $1900 (I don't think the car even blue books for that much!) on a scanner like the one on the Amazon page this in this forum. Is there something less expensive that will do the job? Maybe something that works with a laptop?

patricktoday wrote:

I can do the battery reset again. How long do I need to leave it disconnected for?

A few minutes would be more than enough. I usually install a jumper wire between the disconnected cables to speed things along.

There is no problem with power the accelerator is pushed down that I have noticed. How can I know for sure if the convertor is or is not clogged up?

If you haven't noticed a lack of power, then you're probably fine. All the vehicles I've seen with enough backpressure to open the EGR valve were pretty gutless. :silly:

I am open to purchasing a scanner to resolve this problem. Unfortunately, I cannot afford to spend $1900 (I don't think the car even blue books for that much!) on a scanner like the one on the Amazon page this in this forum. Is there something less expensive that will do the job? Maybe something that works with a laptop?

Definitely less expensive options out there. I've seen the Autel MX808 do a great job on GM's of this vintage:

www.amazon.com/Autel-MaxiCheck-Diagnosti...tions/dp/B07FKZJ86W/

There's also BlueDriver and ThinkDiag, which charge for enhanced coverage on each make. I haven't used the enhanced coverage on either. But it'd probably be the cheapest option to get the data we're looking for.

I just ordered a BlueDriver Module and will let you know when it arrives. Man thank you so much for the help so far! Also Enhanced Coverage is included the BD scanner module.

Tyler wrote:

There's also BlueDriver and ThinkDiag, which charge for enhanced coverage on each make. I haven't used the enhanced coverage on either. But it'd probably be the cheapest option to get the data we're looking for.

I don't think bluedriver charge for enhanced but you might not get any either. The "trust us" marketing is strong with that outfit..........

Autel AP200 should work but I haven't tried one. IIRC first make is lifetime free and you have to pay yearly for additional makes.

Thinkdiag I've used for bi-directional on GM Class 2. 99.9% sure it'll read EGR PIDs. Should get at least 1 make free for a year no matter where you buy it. I got one with all makes 1 year included.

Update

I reset the PCM by disconnecting the battery and shorting the negative and positive removed leads together.

After less than 5 miles the Service Engine Soon light came back on. I pulled over and checked the codes. Again P1404.

I erased the codes (not a reset) and have so far driven the car 73 miles with no Service Engine Soon light on. I obviously don't know if it is going to come back on for the same code or not at this point.

Do you have any thoughts?

patricktoday wrote:

Do you have any thoughts?

My WAG is that the problem is actually happening during most of that 73 miles, just not for 80 seconds at a time. :silly: Getting this code to set may depend on idle time, where you're driving and how many red lights you happen to run into.

Two things generally cause this. One, the wire breaks inside the insulation at the connector and two, it needs the software reflashed. There is a TSB out on it. I did a lot of the them when I worked at Chevy.

Grouchyoldman wrote:

Two things generally cause this. One, the wire breaks inside the insulation at the connector and two, it needs the software reflashed. There is a TSB out on it. I did a lot of the them when I worked at Chevy.

Is this connector also called a pigtail? If so, do I have or do I replace the pigtail/connector? Also, I just recently had the computer updated, is that the same as flashing? If replacing the pigtail/connector does not fix the problem, do I take it back to the shop who flashed the computer and ask them to redo it? Also. I have a BlueDriver scanner on the way. I have been communicating with Tyler. Is there a way to pinpoint said problem by using the coming scanner that you are aware of? Tyler if you are reading this what do you think of this feedback and question I am asking?

Yes, flashing s a synonym for updating the computer. When your scanner arrives you'll be able to read which calibration/program version is written in the computer and compare it to the latest software and to the tsb as well. Reflashing it again would not be necessary if already the newest version was installed. This is probably the case as on 20 years old vehicles you won't see a lot of software updates anymore.

The (short) piece of wiring with a connector that emerges from a component usually is called a pigtail. Often the term is used to describe a replacement connector with wires already attached to it so you can join it easily into the existing wiring.

patricktoday wrote:

Tyler if you are reading this what do you think of this feedback and question I am asking?

No reason to suspect the reflash didn't work. Not yet, anyway. Like Juergen said, we can use the BlueDriver to look at the calibration level and see if it's the latest or not.

A pigtail is a possible suspect, but again, I'd like to see the scan data during the issue first.

The software is almost certainly good.

Update on the situation. I am about to pick up the car from my mechanic. They are stumped and have replaced the EGR valve with 4 different brands. I now have the BlueDriver module in hand. What are the next steps? What are we looking for with this scanner exactly?

patricktoday wrote:

I now have the BlueDriver module in hand. What are the next steps? What are we looking for with this scanner exactly?

I borrowed this scan data capture from ScanShare as an example of the PIDs you're looking for:

www.scanshare.io/share/0j1mOqdUXEGHqd60-dzlbA#3,4,5,6,7,8,9

We're specifically interested in the EGR Position Sensor volts, and the EGR Learned Minimum Position volts. In the above capture, at the cursor, both values agree when the EGR valve is not commanded open:



Hopefully, the scan data will show a clear difference between the two. Remember that the PCM is looking for a difference of .2 volts or more.

Thank you for the replies. I attempted to get EGR information for the vehicle and the app said that further EGR functions are not supported by this vehicle.

As a reminder it is a 2002 Buick Park Avenue. My question becomes would this not be supported by any scanner on this vehicle then?

What should I try next?