Tech who worked on this truck did not get the O2 sensor connector snapped to lock, that is what set the code.
We DID NOT have to tap dance at all today.
We used our SST that we normally apply to our Komatsu trucks, minus the adapter harness that matches the OBDII to the Komatsu diagnostic plug.
When we turned on the SST and ran the diagnostic menu, we saw right off "code P0031", Heated Oxygen Sensor open circuit.
So, Mitsubishi E-26 is P0031 using our Hitachi SST and our Nissan K-21 service manuals.
We also used the SST to erase the code and truck is fine now.
Thanks to all.
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