91 F Body MAT Sensor DTC 23 and 25

[KirkB]

Hey guys, My MAT sensor is stuck at 61 and unresponsive. Replaced sensor and no change still 61. Looped connector and still no change in value, checked continuity from sensor to ECM and all good. This brings me to the pins in the connector or the ECM I'm guessing. Besides looping pins at ECM to see if value changes is there anything I might be overlooking? Using Tuner Pro RT and bins and files seem alright and were found on this form. ECM 1227730

[KirkB]

Watched data while driving today and noticed code 13 O2 sensor set right away. This code had appeared recently but was always DTC 23 and 25 but now with O2 setting DTC 13 ECM stays in open loop and doesn't give it a chance to set MAT codes now. My feelings are that the MAT value had been making ECM adjust A/F mixture as it's been running real rich and probably now took out O2 sensor. Is there a ground connection I'm over looking or just need a new ECM?

[KirkB]

Today I checked O2 for voltage with key on engine off and found no power or ground to sensor. Ohm test on sensor shows it to be in proper order so tomorrow I will test ECM output to wiring and see if just a wire issue or if ECM the root of MAT issues and O2 problems. Anyone with suggestions welcome to help but will post my findings.

[KirkB]

So far with O2 wiring I have found a 2' section of harness that has a break and needs repair. Going to tackle it after vacation with the kids this week as I'd rather open the loom up and repair than just jumping a loose wire around the issue.