o2 Upstream Testing and Questions

[aljenan]

Hi i want to ask if anyone can help me , i want to test the upstream o2 heater and i want to know which wire color i have to test its two plug , one with yellow and blue , other one gray, white , black

just bought a multimeter and doing test by myself

when i test the blank and white it say OL and reading , when i check other plug yellow, blue it say 6.15 around

any guide will be appreciated i am just learning something new and investigating the rich condition which I have