A P0400 code indicates insufficient EGR flow. This could be caused by several things: restricted or carboned up passages, sticking pintle on EGR valve, or a problem with the vacuum supply to the EGR sensors.
The computer commands EGR operation and the Backpressure Transducer measures the...
Todd, I had the same problem in 08. It was a sat fault problem-they updated the computer and no more problem. Also you can try to resend your signal from sirius web site some times that helps. good luck
Bill
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