Spn 2000 Fmi 31 - crm.catalystglobal.com
Websuspect parameter number (spn) and failure mode indicator (fmi) full code list. This list represents text descriptions for faults supported by the powerview 101 and does not necessarily comply with sae j1939. For a specific engine.
2003 31 is what i can found online to be a bad communication issue between the tcm.