What does (Exp) stand for or mean? - 1997 Cadillac DeVille

2012 exp. ?????

P140 means 02 Sensor Circuit No Activity Detected (Bank 1 Sensor 2)

Not sure what "exp 18" means...but the Low Tire Pressure or tire pressure monitoring on the Aurora is done via the wheel speed sensors. Anytime you fill or add air to the tire you will need to reset the tire pressure monitoring - not just the current indicator, but go to gage->tire pressure and reset.
If any of the wheel speed sensors are having issue, this can effect the reporting to the tire pressure monitoring. If you have an ODB-II scanner that can read ABS codes this is very helpful as it will tell you exactly which sensors are having problems.

Don't know what "exp 18" means - please clarify.
Tire pressure on the Aurora is done via the wheel speed sensors. Regardless of whether you have proper tire pressure, you must reset the monitor by going to the DIC-->gage-->Tire Pressure and press and hold the reset button.
You should use and ODB-II scanner to check ABS codes to see if any of the wheel speed sensors are reporting errors. Often times the connectors right at the sensor get corroded and cause issues.

ANY TIME YOU TAP ON A STARTER AND IT STARTS IT MEANS THE BUSHINGS ARE BAD IN STARTER.IF YOU ARE PULLING OUT THE STARTER HAVE IT BENCHED TESTED FOR AMP DRAW TO CONFIRM ITS BAD B.HARRIS Q.S.E. CIRTIFIED 25 TRS.EXP.

Check under the front seats, should be under the drivers seat or passenger seat.

For the 1988 Ford Escort EXP 1.9L In-Line 4-Cylinder:
Firing Order:
1 - 3 - 4 - 2
Cylinders;
.........(back)........
|...1....2....3....4...|
.........(front)
Distributor:
.....(+)-screw
1..........2
3..........4
.....(+)-screw
Let me know if this helped. Thanks for using FixYa.com!

that means overdrive is multifunctioning

you will just have to buy new ones

If there is enough ground clearance than yes you can. It will put a little more tension on the springs but shouldn't hurt anything..