EGR Error Code

Hi all,
I have a '96 TA WS6 with a 6 speed. The car has a little over 40K miles on it. When the car was only a few years old I got a SES light indicating a
bad EGR. The Dealership replaced the EGR and the light went away.
Some time later, the light lit again with an EGR failure. The dealership said the EGR valve was working fine. They worked through their series of checks to determine the issue. They finally came to the conclusion that the passageway within the intake manifold that passes the exhaust gasses to the EGR must be plugged and that the intake must be removed and "boiled out" to the tune of $500. I have a hard time believing that any passageway would be plugged on a car with only 30K (at that time) miles on it. I don't run any cheap gas in it.
When I decided to pass on the $500 fix, one of the mechanics came out and loosened the rubber hose between the MAF and the throttle body and emptied a can of Wynns engine cleaner through the engine. We reset the computer and guess what? The SES light did not come back on. If the passageway was truely blocked, I don't think the engine cleaner would have "fixed" it.
A year goes by and the light is back. Again it is an EGR failure. I run a can of Gumout Concentrated Gas treatment through a tank of gas and the light goes out and does not return.
Another year goes by and the light comes back. I run another can of Gumout and the light goes out but comes back on within two weeks. I tried another can of gas treatment but the light seems to be staying on now.
I kind of suspect a sensor rather than a plugged passageway.
Does anyone have a suggestion as to how I should proceed?
What sensor would trigger the SES light to indicate an EGR failure?
I have forgotten the actual error code. I can stop by auto zone and scan it if need be.
BTW, the engine seems to run just fine and I passed smog two months ago with flying colors. I figure that if the EGR passageway was nearly plugged, there would be some indication in the smog test results. As it was the pollutant numbers were WAY below the allowed numbers. I took it in for the bianunnual SMOG check during the two weeks that the light was out.
Thoughts???
Marshall G. Ward, III
1996 T/A, WS6, 6-Speed, Med Dk Green, Hardtop, T43 Spoiler, 10 Spk CD, Pwr Ant, Graphite cloth, Pwr seat, Keyless entry w/alarm, Leather Appointments Group MODS: !CAGS, K&N, Synthetic Engine/Trans/Diff fluid, Magna Flow Muffler Hotchkis 2 pt STB and SFC's, B&M Ripper shifter License Frame:"One of 2051/1996 Ram Air Trans Am" License Plate: "RAIR TA"
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GM vehicles are NOTORIOUS for EGR valve and passage plugging. The 3.1 engine is a notorious winner of this award.
You can clean out the passages and install an EGR valve gasket with a built in screen. That will slow, but not completely stop the carbonization of the EGR valve pintle.
Get the code you originally retrieved and let's go from there. Joe--ASE Certified Parts Specialist & 10th Ann.Club Tech Director '80 Carousel Red Turbo T/A, 27k orig. '79 "Y89" 400/4 speed 10th Ann. T/A, 57k orig '84 Olds 88 Royale Bgm 2 dr, 307 "Rocket" (lol), 143k and still going....
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What Carb or EFI cleaner does is dissolve the carbon build up in the passage. Using a thru the tank cleaner does it a very little bit. Often a car will not fail until the passage is completely blocked, as well as the pintle as Joe mentioned.
On FWD GM cars I charge $300 to do a EGR clean out. On something like a LT1 or LS1 I would probably charge $500. So I don't think your getting ripped off. It's more labor intensive then it is parts cost wise. You also have the costs of cleaners/solvents.
Usually the cheaper route to go is to start with a clean EGR off a low mileage car that ran well. Then just clean the intake, some times the head ports as well. On FWD cars with the flex tube, it may be necessary to replace the tube. Which is a few hundred more in parts and labor.
EGR system failures are the #10 cause I see of cars failing emissions testing here in Ohio. Charles
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