Check engine light

[99 F-250]

My 99 F-250's coils have been going out and everytime they go out my check engine light does NOT come on but this last time it did. I took it to get checked out at autozone and they said it was the coils. I bought new ones and put them on went back down to autozone to get the codes cleared and they said it was aginst state law. so how do i clear the codes and why did my check egine light come on this time? Thanks for any help.

[12ozd]

Never heard of that before. (guess I'm a criminal then)

Take it to a local shop and ask them,shouldn't be much $ just to clear codes.

Or for about $60 you can buy a "code reader" and do it yourself.
It is not a "scanner", but will simply read and clear codes.
Then you would always have your own.

[kjf-250]

Take all the battery cables off for a minute or so an it'll go off

[senix]

i'd take the batteries off too and try that. Also if the light is on still when hooking up the batteries try driving for a couple of cycles, getting the motor hot and then letting it sit long enough to cool like over night.

A couple of thoses cycles may clear the light as well.

[99 F-250]

Ok thanks i will give that a try.

[Bear River]

With things like misfires, the code will clear itself after the issue has been corrected.

[shorebird]

Take a copy of this to them and tell them that they are not lawers.
http://www.michie.com/colorado/lpext...main-h.htm&cp=
Colorado
toc-indent.gif Colorado Revised Statutes
toc-indent.giftoc-indent.gif Colorado Revised Statutes
toc-indent.giftoc-indent.giftoc-indent.gif TITLE 42 VEHICLES AND TRAFFIC
toc-indent.giftoc-indent.giftoc-indent.giftoc-indent.gif MOTOR VEHICLE REPAIRS
toc-indent.giftoc-indent.giftoc-indent.giftoc-indent.giftoc-indent.gif ARTICLE 9 MOTOR VEHICLE REPAIR ACT
toc-indent.giftoc-indent.giftoc-indent.giftoc-indent.giftoc-indent.giftoc-indent.gif 42-9-111. Prohibited acts.

Go to someone else and have them clear them. If you lived near me I would clear them for you using my Superchips tuner.

[99 F-250]

Ok thank you guys for all your help.

[99 F-250]

I'm so lost right now i took my truck to my friends shop and we hooked my truck up to his computer and it said the only thing it was doing was adding 20% more fuel on the left bank. all the coils are new the spark plugs have less than 10,000 miles on them and i pulled them and they look fine. does any one have any ideas on where i should go from here? I'm going to check the o2 sensor and a few other sensor but im not really sure why its doing this.

[Bear River]

The computer uses data such as airflow, air temperature, throttle position, rpm, and a couple other inputs to determine how much fuel the engine needs. The value it calculates is always the base reference. For this part to work, it assumes all the sensors needed for this data to be accurate. Most of these sensors will affect both banks fairly equally. So if you have a very different readings between bank#1 and bank#2 then suspect that it is not one of the above listed sensors. The above calculation can be thrown off by vacuum leaks. If the leak is unique to one side of the engine, then that side will show a LTFT on that side to correlate it.

All the above is only one part of how fuel trim is calculated. The other part has to do with the O2 sensors themselves. The O2 sensors act as an override. The computer does its calculations, and the O2 sensor monitors the result. If the result is not what was expected, the computer will then adjust the injector pulse width the required amount to correct it. If the sensors are not accurate, they will trigger corrections that are not valid. The O2 sensors can also be deceived by anything that increases the oxygen content of the exhaust, such as exhaust leaks, vacuum leaks, incomplete combustion, etc.