Check Engine Light On

Car was rough running with engine light on. I pulled the Code P0304 indicating cylinder #4 misfire issue. I pulled and replaced the plug and now it appears to run fine, but light is still on. How do I turn it off? Is there still a problem or does it need to clear the Code?

The plugs may be original, car has 100K on it. Plug I pulled is AWSF 42E, is this an original plug? I picked up an SP-486 (AGSF 42FM) at the parts store, is this the best replacement?

is it a motorcraft plug?

if so likly its original


the code prob will eventually clear itself, or you can disconect neg batt for 10 min. or if you have a code reader, clear it with that.


at 100k, if you dont know, i would suggest changing the plugs and wires.

Light disappeared second time I drove the car. Looks like I'll need plugs, wires I'm not sure. They look ok, will probably test before replacing.

as for wires, its kinda one of thsoe preference things.

imo replace the wires, they are almost for sure original, and the 40 bucks is money well spent imo.

others will say as long as they arent damaged, the old is fine.

The reason I'm thinking replacing wires is not necessary is that I drive this car max 2,000/year. It has 100,000 now. 10 years from now, it will have 120,000. I think a good set of wires would be more than $40, closer to $100?

I can see your line of thought.

i paid 60 (just checked receipt) for a set of borg warners. they had some cheapies for 40ish

Plug wires will tend to show more problems in wet weather.....and also in super cold weather (frost)......when everything is stressed out (and when the last thing you want to do is work on your car to get it going).