Hoping for help. I've read multiple threads about o2 sensor heater circuit codes on this and other sites. My 2000 xj with Cal emissions is throwing P0135,0141, and 0161. So far I have replaced both relays in engine compartment, checked and replaced fuse in kick panel, replaced all o2 sensors with NTK's, checked ground continuity, checked power to ECM Pinout, and pulled out harness to double check for damage. All testing was using instuctions from here: http://troubleshootmyvehicle.com/jee...heater-tests-1. With Key on, engine off, no power to heaters. No power with engine at intial start up either. Even though there are only 3 codes, all four of the sensors show no power with voltmeter. Scan tool shows 1 volt at every o2 sensor with key on engine off which is what understand to be a default number the ECM uses when no power is present. Any other ideas? Anyone ever actually solved a o2 heater problem with a ECM swap? Thanks for any help, Dave.