The O2 sensors are readily accessible on the 850's, but some people have had a great deal of trouble getting an old one out. When most folks are doing the work themselves, if they encounter difficulty in removing the sensor, they soak the joint in one or another of the rust-busters that are available, and let it work for a day or two. Then go back and try again. A pro will simply go at the job, and do whatever is necessary to fix the customer's car. The pro doesn't have the luxury of doing it tomorrow.

If you are getting an error code that indicates that the O2 sensor has to be replaced, I'd recommend that you let the current owner get it fixed before you take possession.

I'm not 100% certain of this, but I have come across references which stated that the shift to OBD II came late in 95. If your car does not have the OBD II system, (yours is a 95, right?) it would be a waste of money to buy an OBD II reader.

Again, I've never seen a 95 with OBD II and don't know for sure if any exist. All 96's are OBD II compliant.

Good luck

Marty
'96 855T