P0301 Code Thrown - Resolution | Ford Explorer Forums - Serious Explorations

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P0301 Code Thrown - Resolution


Well-Known Member
October 20, 2003
Reaction score
City, State
Lebanon, OR
Year, Model & Trim Level
1999 XLT
Figured I'd post this in case anyone was interested.

I started getting a P0301 code thrown a while back, and hadn't had the time or inclination to dink around with it, so I've pretty much had my '99 XLT parked for the better part of the past 9 months.

In the last couple weeks, I had need of it, so I've driven it a bit.

My Crown Victoria decided to crap out it's A/C compressor or compressor clutch, and the Explorer troubleshooting became more of a priority.

I replaced the plugs and wires today for the first time since buying it in 2003. It's got 135K on the odometer, and these were the original plugs and wires.

Replaced, and checked the codes again with AutoEnginuity, and it had thrown a P0305 in addition to the P0301.

At this point, I'm assuming that the coil pack is on it's way out, since it appears that cylinder 1 and 5 share the same coil, but after doing the work today, and clearing out what appears to have been a mouse nest in the air box under the filter, the beast is alive again, and running better than it has in a long time.

Cleared the codes drove it around for about 20 miles today, and it hasn't thrown any more, which is nice.

Given the relative inexpensiveness of the coil pack (compared to the feared head gasket/head job), I'll probably replace this in the next few days just to be double sure.

Anyhow, I just wanted to post this, as I've been paranoid about an expensive repair on my truck since it first threw the P0301, and figured others might be feeling the same way.

$65 for some NGK platinums and Duralast wires from Autozone to fix it (and a needed maintenance, anyways), and it's running better than it was before the codes.

None of the plugs appeared fouled, but half of them seemed to be way out of spec on the gap - maybe the electrode was just worn down? Dunno, but they're good now!

I hope you put in iridium plugs. They last longer with more consistent performance during the lifetime.

Tipical neglect - you thought (like many others, no offence) that "if it works, don't do maintenance". OEM spark plugs are supposed to last some 60-80k miles. You leave them in longer, the gap increases and puts a bigger strain on the coils (they will provide a bigger voltage necessary till they crap out).

NGK platinums are what went in, no iridium.

Owner's manual said 100K for plugs, and yeah, it was neglect. I knew it needed to be done, just didn't do it.

I'm up on pretty much every other maintenance, but the accessibility of the plugs kept making me put off that maintenance.

I changed mine (OEM) at 90k and the tip was almost gone, all rounded... Not good for perfect ignition of for the coils - they will generate a higher voltage because of that gap/roundings. Higher voltage means higher power drawn and higher temperature of the coils.