Thread: P0401 code now...

Guess I gotta go look up P0122 to help you. Please hold.

P0122 TP circuit low voltage.
Oh... you really want to read the diagnostic aids on this one. I think part of the answer is right in there.
GearChatter.com :: View topic - DTC P0122

Here's P0121, interesting read on why you aren't seeing it again in the Conditions for setting as well as some more great info that eludes to what the problem could be in the diagnostic aids.
GearChatter.com :: View topic - DTC P0121

And if we read up on the P0401 we can make some correlations from P0121 and P0122 to the EGR code, because it can't even run it's test if either of those are set. Here's the 401 info again.
GearChatter.com :: View topic - DTC P0401 Exhaust Gas Recirculation (EGR) Flow Insufficient

Not sure if you read up on this stuff in the first link I tossed at you. I'd honestly suggest it though. When I read through the what is the pcm/system doing, diagnostic aids and conditions for setting.. I think I see some things that should help resolve this. It's a puzzle though..it's not 100% clear.

TPS from your Gimp to your GP should be the same FWIW.
Plus I'd be checking the voltages and grounds.