Reply To: 2000 GM 3500 FEDERAL WITH RERAR O2S

[none]

A little late but it’s in the OBD reference guide. “Check under-hood emission label to determine OBD certification status. Enter correct result into OIS and follow OIS prompts. OIS may state a BAR-97 test is required on vehicles without OBDII.”

https://www.bar.ca.gov/industry/obd-test-reference