Have the following code tripping the CEL, 0-65551-5, which is knock sensor open. I replaced the knock sensor and did have the ECM unplugged for 6+ hours prior to doing so. I have tried the key on/off 5 times as suggested, have added octane boost to rule out a bad tank of gas, and have taken 7-8 rides making sure the engine came up to operating temperature each time. The CEL remains. Is there anything left to look at before heading to the dealer to have them plug in to clear the code?