BostonSC4

iTrader: (2)

Hey everyone, today has been a crazy day for my SC. I had terrible misfire issues for the past 2 months, and a code 21 popping up. Now, today my buddy and I wired in a denso universal o2 sensor up front right behind the front wheel. I was told code 21 means left bank main o2 sensor. AKA driver side main o2. So we replace that, and I still have awful misfire and the code. Redphoenix told me to get coil packs. I did. Misfire GONE!

BUT THEN, code 21 STILL comes on....its not instant either it takes a few minutes sometimes up to about 15 minutes to come on. Most importantly there is no more misfire. I still have no idea why my CEL will not go off...can anyone please chime in here.

StiCk3

iTrader: (5)

check to make sure that all the wires on the o2 sensor are all intact, i have a frayed wire on my car and it's throwing a code 21 as well.