Resetting the check engine light
Your check engine light is set to come on automatically to remind you of suggested service intervals.It will come on at 50,000miles (80,000km), 80,000miles (128,000km) and 100,00miles (160,000km).The light is set for these intervals so certain parts can be checked for wear or replaced.
If you light goes on at.....
50,000miles (83,000km) The EGR system needs inspection, and the PCV valve should be replaced.
80,000miles (133,000km) the oxygen sensor should be replaced
100,000miles (160,000km) replace transmission fluid
It's been a very long time since I up dated this page , seems like a life time ago (experience wise anyway). So here's an update ,I hope the knowledge/experience I have gained over the years will be more useful to you.
Now for how to turn off the annoying little light
The easiest thing to do is just disconnect your battery count to 20 and reconnect it. This will reset the check engine light and clear the codes. I have been hearing for years about the allusive reset switch. I personally have never found one ,but to be honest I haven't looked that hard as I would rather spend 2 min.s disconnecting the battery then an afternoon searching for a switch under the dash all to achieve the same effect. Now if your truck seems to be running fine and your only sign of any trouble is the check engine light came on. Chances are good the light came of for a scheduled service check (means nothings wrong , just a timed thing) or it can also mean the light it's self is malfunctioning , as Sidekicks age and rust this can sometimes happen. If you reset the light and the light came on for a service check and there is nothing wrong with the truck the light should just stay off now. If the light it's self is malfunctioning one of 2 things will happen.
1. the light will come back on immediately
2. the light will come back on next time you start or drive the truck. this can also indicate that the check engine light came on for a valid reason and the ECM is receiving information from sensors that something is wrong and in turn turns on the check engine light to let you know it has an error code stored.
If the check engine light has come back on after you've reset it and you are unsure or don't think it's just a malfunction in the light it's self you need to Code the ECM (Engine Control Module). For instructions on how to Code the ECM click here and a chart of code meanings click here.