Have 2001 Taurus. Recently, during a cold snap, the check engine lite came on. A diagnostic revealed no hard codes but several monitors have not completed doing their diagnostic. When you turn on the light switch the check engine lite goes off. Any suggestions. Runs great...no problems other than the lite. Has 105K miles and I take care of it.

 

could be just a glitz. I would disconnect the battery for about 5 min. If the cables will touch each other when removed from the battery , Its a good idea to touch them together for a min.

This draws any laying juice from the system , Then hook up your battery , start the car let it idle a couple minuets, Before you drive it, might take a couple miles for it to relearn whats its suppose to do .

Hopefully that will clear the lite problem, if not , then I would suggest trying to pull the codes again.

TADAAAA post # 500..hooyaaaa

 

Unhooked battery for 10 minutes, touched the two cables together to be sure of draining the system. Re-hooked the battery and started...results remain the same. Check engine lite comes on. Did a diagnostic, no hard codes just indication of sensor monitors not completing their start-up check. Baffled?? Check Engine lite goes off as soon as you turn on the head lights.
Larry

 

probaly a faulty puther if it cant self test , thats been my past experanice. I would try unplugging the puther an cleaning the terminals with some electric contact cleaner an then restest , prehaps it got some moisture in it.

I worked on a 88 E150 van that the heater core had been seeping , an the puther was mounted just below it , there was traces of coolant in the puther housing , which was making it do some real funny things with the self test , an the check eng lite

 

I have same exact problem with 02 taurus....weird.