If the check engine light is on, there is a definate reason it's on. The check engine light is an warning lamp to let you know that an emission component is malfunctioning or wearing out, both of which can adversely affect your vehicle's operation. When you scan the computer for fault codes that the check engine light indicates are there, it will point you towards a malfunctioning component or towards a sensor that is accurately reading a certain engine parameter that is falling outside the manufacturer's specifications, i.E, fuel ratio, EGR valve position, etc. If it comes back on or is still on, let us know what code is pulled from the computer.
I knew one explorer to have the problem you describe. It was a bad coolant temp sensor. It "painted the picture" to the vehicles's computer of the vehicle always being warmed up to operating temperature. I've also seen it the other way around, where the vehicle would idle extremely high, especially when warmed up because a bad coolant temp sensor read the vehicle as always being cold.
The check engine light is NOT the ultimate diagnostic tool, but in this case it seems to be trying to tell you something. Before you replace anything, pull the codes, see what they have to say, and start there. I hope this helps.
Monday, January 15th, 2007 AT 11:47 PM