My wife's 06 Expedition has had a Engine Failsafe Mode happen 3 times now on cold days (below freezing). Basically it flashes Failsafe Mode and the engine dies, and as my wife says, She can't steer, she can stop, but it scares the hell out of her, particually this last time when she was in heavy traffic going 40MPH. I took it to the dealership since my code reader won't do CAN. Anyways, they told me they don't quite know what the exact cause is, but know it has something to do with the throttlebody, maybe sticking and if it keeps happening, that they can replace the Throttlebody. My guess is the TB sticks open and the engine shuts down for safety reason, but I might be off. Anyways, anyone else had this happen, know if there is something easy to fix it like cleaning the throttlebody, greasing the drive by wire gears, etc. Don't worry, it has 75K miles on it so warrantee is long gone.

My other thing new that is happening is on cold morning, it been getting down to the teens at night which is darn cold for this part of Arkansas. When the trunk sits over night or even for a few hours and get cold, there is a noise that sounds like something rubbing in the front end for the first hafl mile or so then it goes away. Its a 4wd so I was looking under the there for an axle rubbing, but it only does it when it cold. I got new brakes for it 2 months ago. Any ideas?

 

Remove the front wheels and look closely at the relationship of the calipers/pads and the brake rotors. Just a guess, good luck with it and let us know what you find.

 

They don't know the cause? Surely you jest my good man!

Engine Failsafe Mode kicks in when there is a misfire sever enough to put enough unburnt fuel into the exhaust system to destroy the catalytic converter. By shutting down the engine, failsafe mode is saving you the rather expensive cost of replacing the catalytic converters on the truck.

Did they even bother to check for any trouble codes?

 

could be your tp sensor they can cause that issue then later when you go to test it, it shows normal

 

I'm sure they did. I use these guys regularly for oil changes (i'm lazy and it costs about the same to have them do it than for me to buy decent oil and motorcraft filter) and stuff I can't do like pull codes. Plus I used to have two friends that were mechanics there. I was under the impression that they ran the codes since they charged me for it. I picked it up after 5:30 since I had to work. I asked to talk to the mechanic, but he had already left. The service rep (a new guy) said the only saved codes involved the throttlebody and they couldn't duplicate the fail safe. He said Fail Safe Mode could happen under several different conditions, and said if it kept occurring, that they could replace the TB. I did some searches before posting here and there are other people that have had all kinds of problems including sticky TB's that can cause fail safe mode. I was looking yesterday at pulling the TB, but I did have a whole lot of time and everything was still hot. It looks pretty involved so I wasn't sure if there was any common problems that has an easy remedy.

I forgot to mention on the front end noise earlier, that I got caught in the river bottoms for a good rain storm during the spring. I had to go to requalify at the range so I didn't have much choice. The roads were like creeks. I noticed several times when I got where I was coming out of some deep slick stuff that the front axle would squeek for 50 feet or so. Ive been wondering if a wheel bearing or ujoint can do that or maybe it might just be normal. I wonder now if the may be related.

 

It's not normal and it could be either of these. You have a 2H on your shift selector switch right? In 2H the front drive shaft does not turn. So if you get the squeak when in 2H you most likely have an issue with front wheel bearings/hubs and not the u-joints.

 

The squeek only happens when you drive through water and it doesn't sound like its coming from the brakes. I believe the hubs are always engaged so you would think it were a bearing you would hear it all the time. What concerns me is the cold rubbing noise. I'll get it up in the air next week when I am off again and see what I can find.