Ok so don't damn me to hell for asking this because I didn't search too hard. I ran my CE light and it cam up 21 22 and 27..I know 1 of them is heated oxygen sensor/oxygen sensor signal and the other is water temp sensor the last one is sub-oxygen sensor circuit or sub-oxygen heater circuit. Can someone tell me where they are? And how to change them

 

27? You have interpreted the codes correctly, but the sub-O2 sensor is only on California spec trucks. (Maybe Canadian, too.) Is yours imported?

You might try re-checking the codes (it can't hurt). Then take a look downstream of the catalytic converter for a second O2 sensor. That's it.

But before you go charging down to the parts store, remember that these codes reflect a problem in the CIRCUIT, not just the part. The connectors for the o2 sensors are hanging under the truck, and if you break a wire ... that's the circuit. At the age of your truck the o2 sensors are maintenance items, so it won't hurt to change them, but don't expect a miracle.

 

You are correct it is a CA truck so it does have all the emissions stuff. Im pretty certain I read the codes right I have a video I'll post if I can figure it out. But I did do a rebuild and had to pull all the wires that wrap around underneath...which was a huge pita.