New VX owner here. '92, fed, 211k. Bought it with the CEL on. Came up with code 48. My Hanes manual said to check the voltage to the O2 sensor heater. If I understood correctly, I was supposed to get "battery voltage" for pins A and C on the engine side of the O2 sensor harness. I got 6ish volts... The manual does not say what to do if improper voltage is present. Any ideas?
Before running the codes, my gut instinct was to just replace the O2 sensor... now I think I will wait and see if there isn't another problem present. The car is getting 35ish MPG, idle at 1kish, and the shift light is inoperable, if that helps the diagnosis.
If you have a check engine light with a code of 48 and your shift light doesnt work and your getting only 35mpg, I put my money on the O2 sensor. Go ahead and unplug the sensor and see if there are any changes, if there isnt then its 100% the sensor.