02 Ford Explorer P0351 Error Code?

Check engine light just came up and this is the code I got. P0351: Ignition Coil "A" Circuit Primary/Secondary Malfunction

My car still runs just fine. No loss of power, no rough idle. So… Can I fix this myself and how?

Yes, replace the ignition coil

2 ways the ignition coil will develop a problem that sets the p0351: [one] Coil pack starts to leak electric current from the primary side to the secondary side, and [two] the sensing line from the coil primary to the computer starts to get a dirty connection. It is better to clean up each of the electrical connections to the coil pack before replacing the coil.

If you disconnect the electrical connector plug from the coil and resistance measure from the left-hand pin to each of the other pins, they should all read the same. Those are the primary side resistances. If you then read the resistance between the 2nd pin and the left-most spark plug wire output connector, that is the primary-to-secondary resistance. Move over one pin and one output connector and same thing and so on. If you have the bad primary-to-secondary condition the code is setting for, you will see one of those pairs of resistance readings go down compared to all the other pairs. The primary-to-12v input will be lower than the other cylinders, and the primary-to-secondary will be lower than the pri-2-sec for the other cylinders.

If all the pri-2-12v are the same and all the pr-2-sec are the same, the problem is in the wire connections to the coil that the computer gets its measurement from.