My '02 F150 4.6 Supercrew just turned on the Check Engine Soon light.
A code scanner said P0306. In the past day it had developed a small miss then turned the light on 200 yards from home. The last time i saw these symptons on this truck was in 03 on interstate. Pulled it into a Ford dealership and they kept it a month and rebuilt the engine in a truck w/less than 18K on it. Quality is job one unless it costs money. An injector had locked open, it suffered a hydraulic lock and bent a rod and a few other things. Now I've got the same symptons. If it is the same problem it might blow the engine in a 10 minute drive to a dealership. Wish it had the first time.

My question: are there different lights that it can turn on? Like a "Check Engine" for things that could maybe wait and "Check Engine Soon" for things that may be catastrophic.

Any advice about things to check would be appreciated.

 

P0306 Cylinder #6 Misfire Detected. get it checked out soon or risk toasting your catalytic converters.

 

If you have a solid "light on" situation and the scanner read 306, you have COP primary failure. Replace COP 6 and you'll be good to go

Letting this problem go can have problematic effects - so fix it ASAP.

 

Parden me for saying this but you can't be thinking in these terms without any basis in fact.
Get the code and service for the indicated fault.
This is a new fault and should be treated as such.
As far as what will turn on the check engine lamp----only about 1000 codes.
Take your pick. That's why it foolish trying to second guess and driving yourself nuts over it untl you really know.
In answer to your first post.
Good luck.