Service engine soon light just popped on in my gf's neon. What causes it and how do I get rid of it? Any specific sensors? 70k miles and climbing..

It could be caused by 100's of different reasons. The first thing I would do is find out what code(s) it's bringing up. This can be done by cycling the key on/off three times then count the series of flashes between the pauses. ie: 5 flashes-pause-1 flash =code 51. It will start over again- with other codes. Let us know what you come up with.

Just go to any big chain store like Auto Zone, Advanced.They will pull codes free.That will tell you what code.That will at least give you a starting point.Rocky

The Service Engine Light has came up on my 1998 Neon twice in the last eight years. Both times it was a "a cylinder mis-fire". Car ran fine when the light is on, so the it was just reset.

With the information you provided it should be fairly easy to diagnose, don't you think? You have to SERVICE the ENGINE but did it say exactly how soon to service? Maybe you need to read it again Sorry man but you can't be serious