Last week the engine light came on steady in our 2016 Expedition with 155k miles. Took it in, got it scanned and was told it was the #2 O2 sensor. Was told it was okay to drive but should have it fixed when possible. The engine light went off and on again a couple times during the weekend. Monday on the way into work the light came on and flashed a few times and then started running really rough. Got to work and called the shop that does work for the dealership where we bought it in May. Left the vehicle there.

Just called him to see how things were and he said he thinks it is the Bank 1 timing chain. He also said it will be an expensive fix, guessing $ 3-4k. Now, I honestly don't know the guy and have not built up any confidence in him.

Posting this on here to see if anyone else has had a similar situation and can give me some advice.

Thanks!

Moosetrot

Is yours Ford a V6 or V8? On the V6 the engine will need to be pulled or the transmission dropped and I think the V8 is the same. From what I have been told is that these engines need regular oil changes with good oil and filters to prevent the plastic/nylon tension cassettes from wearing out to reach a acceptable engine life span.

If it’s the 3.5 eco boost it could very well be bad plugs. That motor eats plugs a lot, actually cracks them sometimes. That’s where I would start. They are easy to get at yourself, use motor craft plugs.

You can drill a small hole in air cooler so water leaks out instead of being sucked up and contaminating plugs. Lots of YouTube stuff on it. I did it to the 14 f150 eco I’m driving about 60k ago. Smoothed idle out and no bad plugs so far.

I have always said, the Ford 5.4 and 3.5 need the oil changed every 3000 miles. Or you will have trouble with timing chains, Cam phasers. I change my oil every 2800 to 3200 miles on my 2013 F150 3.5 191000 miles. A 2015 Ford Expedition 3.5 with 180000 miles and a 2019 F150 3 5 with 150000 miles. I change spark plugs every 80000 miles. To me the Ford are the hardest vehicle to throw a check engine light on.

I run Mobil 1 and Motorcraft FL-500 filters. I buy them off Amazon by the case.

My guess is that there are two separate issues. The oxygen sensor code is for the post-convertor sensor it just monitors the health of the catalytic converter and can likely just be fixed with a new sensor. It possibly could be related to the misfire codes (see below) but can't tell without knowing the actual code.

The flashing check engine light indicates a misfire bad enough to damage the convertor, so there will definitely be a misfire code stored. I'm guessing you've got the 5.4L 3V engine. They were notorious for timing component failures. Usually not the chain itself, but the phaser (cam.gear with the ability to change timing) and or cam timing solenoid. A fellow could remove the timing cover and such, and replace all the timing components, but it's not necessary. If it's just a phaser, there's a special tool that gets shoved down the timing cover (with it still on the engine) that will hold the chain so the phaser can be replaced with just the valve cover off. The solenoid can be replaced with just the valve cover removed.

Knowing the codes pulled by the scan tool would tell the tech which way to go as far as diag and parts replacement. A scan tool can control the cam timing, and can be used to determine what parts have failed. If it truly is the actual timing chain, then of course the timing cover will have to come off and at that point with those miles, you're best to just replace the guides and everything while you're in there.

They quit putting the 5.4 in the Expedition in 2014. In 2015 they went with the 3.5 Ecoboost.

It is the 3.5 Ecoboost 6 Cylinder.

Went over and talked to the guy. I at least expected him to have some printouts about the codes he found and what he wanted to do with it. Instead he told me it was going to e $4189 to fix it and said he was using all Ford parts because they were cheaper than aftermarket. I asked him again if he had anything printed out for me and he pointed to a little notepad with his scribbles on it. I asked about warranty on the repairs and he kind of shrugged his shoulders and said the warranty on the parts is usually 90 days.

He might be a good mechanic but I have no confidence in him and that is a lot of money. I have been told by a few folks that a Ford dealer would warranty the repair for 2 years. By what I have red this is a fairly complex repair and I figure a Ford shop would at least have some experience with it and probably whatever diagnostics they may need to get it done and done right.

I told him I would need a couple days to figure out what I was going to do.

Going to drive (our other car) to the Ford dealer and talk with their service guys. Talked to a neighbor who used to be a Ford mechanic and he agrees to stay away from this guy. I know I might take it in the shorts but I am old enough to try to make this our last car and so want it done right. Wonderful Wife absolutely loves the vehicle and so it will be worth it to happy to be getting into it and not worrying.

Thanks for the help!

Moosetrot

Might just be a bad coil pack.

3-4 grand how much to swap a motor? Me I’d do it myself if it was my vehicle but that’s my wheelhouse and I’m cheap.

Common problem on Eco Boost 3.5. The round pins that hold the cam phasers eventually elongate the pin holes. Ford came out in about 2021 with new square pin set-up and updated phasers springs. Make sure when its reoaired that they don't put in NOS parts. Demand the new stuff. My friend has a 2017 F150 that had the same problem.

Here's a link to an independent, certified Ford tech on Youtube. He's a wealth of knowledge if you own a Ford product.

https://www.youtube.com/FordTechMakuloco

He's covered this topic in videos several times.

Why have you not taken it to the Ford dealer to have them look at to tell you what to do? They're Ford. You should ask them what to do with your Ford.

I didn't buy it from a Ford dealer, just a used car lot. They also own a repair service and that is where I took it. That will not be the place that will be doing the repairs.

Moosetrot

Talked to a certified Ford mechanic at the Ford dealership. Having my vehicle towed over there. We are going to start over with diagnostics from square one. I feel a heckuva lot more confident than with the first guy who looked at it.

Moosetrot

It won’t be cheap at a dealer compare hourly rates first they can be high sometimes a good repair shop is cheaper often flat price VS hourly book price.

If your not hearing a noticeable rattle/ticking on start up my 1st guess is bad plug or plugs 2nd is coil pack. Code reader should tell which cylinder is having the issue.

It would suprise me if a motor swap would cost double the price.