A few weeks ago, while playing in the mud, I had a misfire on #5 on my 97 F150 with the 5.4 in it. Sprayed some silicone on there and it quit missing, but the check engine light stayed on. I figured the wires were wet and the silicone would solve the issue It did, but left the light on. I changed the air filter a few days later, because it was about time for a new one. Started it up and the light went off. Well, the other day I went through the car wash, light came back on. Had it read at Auto Zone, misfire on #1. I figured since it was only misfiring when it got wet, it had to be the wires. Changed the wires (well, boots, whatever they are called...) and the light is still on, but the truck doesn't feel like it's missing at all now and it does run and start better from what I can tell.

Now my question is, does the check engine light turn off as soon as the problem is fixed or does it stay on for a certain number of driving cycles before it clears itself? And if it clears itself, how many times does the truck need to be started and how long does it have to run for if it doesn't clear it as soon as the problem is fixed?

Thanks in advance,
BT

 

Drive cycle related unless cleared with a scanner.
Don't remove power just to clear it. This causes a full loss of other stored data for long term corrections that has to be found all over again and takes some time unless you don't care.
One full driving cycle is more than 50 miles and has to meet all and certain driving conditions just for short term learning..

 

So if the problem is cleared, it can still stay on, but will turn off in how many driving cycles of 50 miles?

Might be easier to just get it cleared. lol

 

It will stay on after the problem is fixed.

I bought a $100 reader/reset tool at pep-boys just for this reason.

Its well worth it.

 

Been debating on getting one... Probably would be a good idea. Thanks.