Hi all, it's been awhile since the last time I was here. My poor old 89 240 has mostly been parked for the last several years. I got it out the other day and noticed that the O2 sensor wasn't working too well. I replaced it with an NTK brand ( I'm not a big fan of Bosch anymore) anyway after replacing it my air control meter stayed at a steady level even after several minutes of warming the engine. If I kept the engine running above an idle it seemed to register correctly. Ok long story short, the O2 sensor is not getting any voltage to the heater side of the sensor. What I need to know is, Where does the O2 sensor get it's heater voltage from and what if any relays are involved? If anyone has a wiring diagram I can refer to or if anyone can just explain the most likely cause for the loss of heater voltage I would greatly appreciate it. Thanks for reading my message. Max. P.S. HI Art, been awhile.