I was going thru the steps to check/adjust my apps voltage, and after I adjusted the sensor I realized I had left the ignition on. Now the CEL is on but its running fine. Did I do any damage by leaving the ignition on while adjusting the apps sensor?

 

no you have to have the ignition on to test the voltage on the apps. i did the same to mine with no problems..... the apps voltage is on the back side of the apps it will be in .000 reading. desconect the ecm conection behide the air filter and test number 23 pin ( I think) to test voltage with power on.

 

Nope. What happened is that you probably through the reading out to far and tripped a code. Clear the codes and the light should go out and you shouldn't have any problems.

 

I've got a multimeter with clamps that go around the wire to test it but when I do that, it drops to zero. Do I have it on the wrong setting, or should I use the probes?

 

My voltage is a little higher than the apps sticker. I've read about apps problems where voltage is too low, could higher voltage cause problems also, & if so what would they be?

 

If your multimeter is analog then it is possible that it is drawing too much current and you need to use a digital meter. Not sure what you mean by probes but if the clamps you refer to are the alligator clips then they will work just fine. I am guessing the probes you refer to are test prods.