*%@&!!!!(Swear words) 'Engine Failsafe Prog' [SOLVED!]

[1BADM6]

I guess I am welcoming myself to E53 ownership. I got the Engine Failsafe Prog CEL today, no throttle response and crappy idle. Fortunately it happened in my driveway. I'm hoping it's my battery because, as a new to E53 owner, I sat in the cabin with the music on while reading the manuals. I didn't think I was in there long enough to drain the battery but I also don't know how old it is. I'll check voltage in the morning. It was running great after the gym and all of the way home. No other CEL's were noticed. The PO did say it was needing valve cover gaskets and there is minor evidence of leaks. Outside of that they are dry and I also have a suspect CCV. I have the replacement in hand.

I've searched all over for my OBD2 reader so I'm kind of going at it blind. I might pick up a generic one before I get a bimmer specific diagnostic/coder. Wish me luck.

[SOLVED!] - She's running like a dream! I removed the intake, cleaned the contacts on the connectors and MAF. Everything looked spotless, no cracks, nothing blocking the butterfly. I'm really just going blind without the right equipment and a manual. I was in the process of replacing the CCV and stripped 2 of the torx heads. The upper one I can deal with but the lower one I don't see a solution outside of pulling the motor so, I'm going to put it back put the screws back and dwell on it for a bit. The bolts seemed factory tight and the ones I did crack really took some effort.

After putting things back together and making sure the connectors were secure I crossed my fingers and fired it up. I fully didn't expect it to purr like it did and intently listened for erratic idle and looked for fluctuations in rpm but there was no such thing. I made sure I grabbed my phone before I went on a test drive and I'm happy to report there were zero issues outside of my failed CCV replacement attempt. Either MAF or the connectors were the culprit. I really wish I knew which. I don't think it was the MAF connector because I muddled with that before I dug in to things. Most likely the MAF was dirty even though it wasn't visibly so. I'm going to change the title of this thread so it can be referenced easier in search. Thanks for the input.

[*UPDATE*] ETA, the following morning. Engine started fine this morning, much to my chagrin, but...when I accelerated out of the driveway the engine stalled, no throttle and the same "ENGINE FAILSAFE PROG" error in the dash. I limped it back home, parked it and fiddled with the MAF sensor. It had either come loose or I did quite seat it enough in the receptacle. I felt the faint click, turned the ignition on and she fired up with no more issues throughout the day. This all appears to have been a dirty connector or MAF sensor, not ruling the latter out. I'm going to take a closer look at things to make sure all of the pins are seated and there is no corrosion in the plug or receptacle or frayed wires. They wires make a 90 degree bend coming out of the plug and no tape or heat shrink at that junction. I will improve that and zip tie the plug cover to the wire loom.