So Im on the way home, after just fixing my knock sensor less than a week ago, and the SES light comes on. I checked to see what codes it was throwing, and it gave me
0309-undefined
0705-EVAP
Has anyone ever seen the 0309 code before?

Also, when I did my knock sensor I unplugged the evap for the time that I did it. This caused it to throw the code once before. I have since reset the ECU. Could this just be the cause?...or is there yet another problem?

 

I would wait to see if it pops up again after resetting the ECU. See what you get for codes if it comes up again. I have never seen the 0309 or anyone every asking about it.

 

I had been getting 0309, 0903, 0705 for awhile now and I just replaced all the hoses in the engine bay that goto the evap canister/valve system and they haven't come back on in almost two weeks now...

hoping it was caused by an airleak in a hose, they were the original OEM hoses that were baked solid by heat (didn't look cracked, but they were so stiff I'm thinking they werent making an airtight seal where they connected to the canister/valve system.)

I would definitely change these hoses first and see if it eliminates a possible air leak (the hoses are 3/8" diameter.) Couple dollar solution that may work out for you.