Help, My 2004 Silverado had a check engine light on, C0269, I'm pretty sure I fixed that, Sending unit, gas line, bla bla, but I also have P0157, I checked my O2 sensor with a meter and it appeared to be junk. I replaced it with a new one, pulled cable off of battery for about 5 mins, still showing code, it's there right at start up. Is this normal. Need to get inspected overdue. Thanks