Well, you have two O2 sensors, and the best clue is if you get a check engine light. If you don't have a reader (I have a ScanGuage II mounted above my RR mirror that gives me all sorts of extra engine data, including the ability to read a CEL and also to clear them without disconnecting the battery), you've have to take the car somewhere to have the CEL read.
P0170- generally means front sensor (just below turbo) has gone bad. I had this CEL and replaced the front O2 sensor, it hasn't re-ocurred.
P0173- generally means rear sensor (after catalytic convertor) has gone bad.
Trouble codes on your car, go to 95 Eclipse (Turbo) 96-98 Vehicles OBD2
There are other trouble codes that show if your O2 sensor heater has crapped-out.