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Jeremy, Certified Diesel Technician/Electrician
Category: Ford
Satisfied Customers: 3320
Experience:  ASE, NATEF Engines and Electrical certified, EPA 608/609
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Error P0678, yep scann tool II 62,000, 2004 F250, just

Customer Question

error P0678
JA: How many miles are on the car? Do you have scan tool or a code reader?
Customer: yep scann tool II 62,000
JA: What is the model/year of your Ford?
Customer: 2004 F250
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: just starting the process
JA: Anything else you think the mechanic should know?
Customer: nope.. pretty basic.. Its plug 8
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Ford Mechanic about your situation and then connect you two.
Submitted: 1 year ago.
Category: Ford
Expert:  Jeremy replied 1 year ago.

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Customer: replied 1 year ago.
I see that error popping up now. About 9 months ago.. i changed the main computer board ( reason.. it was tossing all sorts of code.. and hard starting .. and sputtered) .. all went well .. been great since.. a week ago..
Expert:  Jeremy replied 1 year ago.

Did you replace the glow plug? The glow plugs do go out on these. Try replacing the glow plug and if it pops again, then check the harness back to the module. With it being just the one glow plug coming up, it is typically the glow plug or the harness to it. If it was several of them at once, then I would lean onto the module. In this case, I would swap the glow plug out.

It won't derate (limp mode) the engine and the vehicle is still driveable. It just states that the glow plug on cylinder 8 is showing low resistance on the return indicating the glow plug is bad (or the harness connection).

Customer: replied 1 year ago.
ok.. any easy way to go this.. as changing the computer module was a real rascal ... stupid question standing in front... plug 8 would be left or right.. back or front one
Expert:  Jeremy replied 1 year ago.

Passenger back is 8.

Customer: replied 1 year ago.
i was afraid on that.. the hardest one to get to .. any tips on changing that one
Expert:  Jeremy replied 1 year ago.

Not really, unfortunately. I know it is a pain for that side. I remove the valve cover then slide it forward so I don't have to pull the turbo. It is a lot easier to get to if the turbo is pulled.

CLICK HERE for a video that Ron did on them on that side. He's a tech I used to work with.

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