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EricFromCT, Ford Technician
Category: Ford
Satisfied Customers: 3964
Experience:  20 years dealership exp., ASE A1-A9 L1 L2, Ford Lincoln Mercury Senior Master, Diesel Certified
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Last week I replaced the plug wires on my 2003 f150 4.2

Customer Question

Last week I replaced the plug wires on my 2003 f150 4.2 143300 miles. It ran good until this morning. It is putting out codes po303 and po316. I put old #3 plug wire back on and no change. Read coil 2nd resistance and got 1800 1900 on all 3 pairs . Could it be a bad coil pack. Any help would be great.
Submitted: 1 year ago.
Category: Ford
Expert:  EricFromCT replied 1 year ago.

Hi. It is possible that you need a new coil pack. Although your resistances seem ok. Sometimes what you can do to check the coil is to remove it and inspect the underneath of it. A lot of times if it is bad there will be a crack on the bottom side of it.

Expert:  EricFromCT replied 1 year ago.

You can try that or you can just purchase a new one and put it on. If that does not fix it, you could always return it.