2008 Ford Expedition 5.4L Code P0012 Fixed by Computer Reset?

yes what that is the cam is overretarded and the pro used the scanner to reset the keep alive memory in computer and probably tightend your battery cables.

the P0012 code is in relation to "camshaft sensor" over retardation in relation to the "crankshaft sensor". this is usually caused by a plugged/stuck VVT solenoid, and can usually e fixed with the removal, cleaning with brake cleaner (or carb cleaner) to clear all the inner passages and screens on the VVT solenoid. before reinstallation of the solenoid you should hook up the solenoid to the battery and listen for a 'plunger' sound coming from the power being provided and disconnected. if no sound is present, replace the solenoid. If the P0012 code persists after resetting and the cleaning, you will then need to address the VVT Phaser Camshaft gear, located under the valve cover and is the gear with the tabbed ring gear, springs and gear teeth device with a timing chain over the top. replacing this is relatively easy if you are familiar with engines and specifically the 5.4L3V nuances. a mistake here will end up being a full timing chain, guides, etc.. repair. Best left to a professional, with the correct wedge tool (to keep the chain in place while top gear phaser is removed) and cam shaft locking device (to keep the cam shaft in the exact spot that the phaser was removed at. This will make the reinstall of the new phaser a snap and pretty much fool proof. The easiest way to diagnose the camshaft phaser issue is to listen to a 'click', click, click..... Noise coming from teh front of the engine while it is idling. That clicking sound is the phaser and solenoid reacting to the engine and the inability for the phaser to correct itself properly. To some people it might sound like an extremely loose rod 'rattling around, but that is not it. its the phaser.

Nice! well put, I agree with everting you said here, are you a mechanic?

I am NOT a mechanic, in the sense “did I attend school to learn the trade?”… but I’ve been wrenching on my vehicles since I was a teen barely out of high school. I learn through research and “hands on” trouble shooting. This particular issue is something I had recently gone through and thought I would share it in the hopes it prevents someone from being told,” it’s a timing issue and will require a total timing chain, cam, and gears replacement…. This will cost up wards of $3500.00”. To the elderly lady, this is a lot of money, and why not educate people against unscrupulous “mechanics”?… the job, booked in the shop, is in excess of ‘10 hours labor’, but can be performed at home, in your garage with the correct tools in a few hours. I hope I have answered your question and provided the insight you were seeking.

Nice! that is the way I learned as well, pay yourself to learn or pay someone to teach you, both ways work.