I have a 2002 X5 3.0i. My service engine soon light came on today, and I went to autozone to check out the fault code. The code came up P0174, oxygen sensors. Could this be related to having straight pipes?? Should I put my resonator back on before heading to the dealership to have the sensors replaced? If they notice any welding near the resonator, will this void my extended warranty? Anyone know anything about this? Suggestions are greatly appreciated.