I have a 2005 Expedition that left the wife wife on the road yesterday. The truck had went into failsafe mode. I got to the truck 30 minutes later and drove it home with no problem. It had codes P0121, P2104, P2112. I did a little research and bought a new Electronic Thottle Body from Ford. A friend in the parts dept. said he sold 2 a day. I got home and changed it. I had the battery off for hours. Now the truck stays in failsafe mode with codes P2104, P2111, P2112. P1000. Any suggestions? Mike

 

Replace your spark plugs. An overly large gap from worn plugs creates RF interference. There's an outside chance one or more of the COPs are causing the issue, so make sure you inspect those good when they come out to change the plugs.