Trouble Codes, No End In Sight!

Friends,
My cousin has a 1997 Buick Lesabre. On Thursday his MIL came on and I used a scanner to get the code. I don't remember exactly what it said but it
was something like the "O2 sensor, bank A, CKT" The auto store had me replace the sensor and I cleared the codes and it was okay until today.
Today my cousin said it started to run rough for a few seconds and the MIL came on. The codes I got are:
P0121: TPS/PEDEL POSITION SENSOR A CKT RANGE/PERF
P0121: PD (saa,pending)
P1406: AUXILIARY EMISSION CONTROLS MANUFACTURER CONTROL
I really feel bad for him. He's in his eighties and has had a lot of car trouble. Does anyone have any ideas?
Thanks, Steve
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I
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the MIL

car
This sounds like an EGR problem. It could be sticking or clogged. Usually, you would use a Tech 2 to run it through its range in the test mode and see if the actual reading matches the desired setting. But if you don't have such an animal, you could remove the EGR valve and check the pintle to see if it is all carboned up. With this electronic valve, you really need the right scan tool to avoid buying buying something you don't need. Unless you have access to a known good test part or junkyard. You would need to start with this code first, fix it, clear the codes and see what happens.
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Thanks for the reply "R". I guess I'll try to remove and clean the Conventional EGR valve. I found the digital EGR BUT I can't find the stupid Conventional one. I'm looking at the Haynes manual and it says it is on the "firewall side of the intake manifold". They have a photo but I just can't figure it out. Assuming you are talking to the village idiot (which is close to the truth) could someone please tell me where to find it with as much detail as possible including "landmarks" and how big it is?
Thanks again, Steve
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I think there is only one EGR .. But I don't have a book to look at either.

stupid
the
can't
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There's only one EGR. P1406 indicates that the detected EGR valve pintle position was too far off from the actual position. This could be caused by the valve being clogged up with carbon. The P0121 code indicates that the predicted engine throttle angle is not close to the actual throttle angle, but the service manual notes that a stuck open EGR could set P0121 and if P1406 is set, diagnose it first.
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Robert Hancock Saskatoon, SK, Canada
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You must have misunderstood. There is only 1 egr and it is electronic. It has an electrically driven pintle. When they fail, the pintle can stick open, it can also stick when dirty. That is where the test equipment comes in. But if you have no way to have it properly checked, I would take off the electronic egr and flip it over to see if it is all carboned up. Spray it with carb clean and reinstall it. What have you got to lose?

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the
Don't forget to check the base plate, and intake port for carbon. I recently did a EGR replacement on a 93 Grand Prix 3.1 V6. The EGR was bad, and the intake port was 100% blocked. With the port cleaned, and a used EGR, it passed the Emissions test with room to spare.
Recently I have seen allot of EGR related emissions failures. Usually with very high NO levels. Charles
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