Trouble Codes, No End In Sight!

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.

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

I think there is only one EGR .. But I don't have a book to look at either.

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.

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