Originally Posted by Viper1

So I switched out the intakes to the K&N Typhoon and added a Gemini cat back exhaust The car ran great the few times I took it out then went to drive it and the check engine light comes on. Car goes into a limp mode? Brought it back disconnected the negative battery cable....good as new....drove it a few times and now it happened again! Except this time i took the negative cable off for only a few seconds and the car pulls like it should but the light is still on! Any thoughts? Maybe an O2 sensor?