i pulled a code 63. i think a code 63 is primary O2 sensor. car is in limp mode right now, at roughly 4000 car stops making power. just runs like ----. replaced sensor and still have code. so took it to advanced auto parts and they said it pulled an engine miss fire or ignition problem. so im stuck i need help. what could it be?
thanx STOCK SUX!!!!!!!!!

 

well the code 63 is the secondary sensor, so I would check the one further down the exhaust path.

The limp mode is what is making it run like ----.

 

what car? what year? i'm assuming obd2 since you have a secondary o2. teh secondary o2 sensor won't make the car run like ----, more than likely, you do have a misfire problem somewhere, that will deff. make the car run like ***. check your plugs and plug wires.