Q&A

I want to help, but I'm unsure what your question is?

Did you clear the code after the repair? Did the check engine light come back on?

The PO325 knock sensor code is common on many Nissans, it doesn't bring on the Service Engine Soon if is performance related, it will bring on the light if the sensor goes open circuit.. These engines just always seem to have that code when you are presented with another trouble code, so go after the Oxygen Sensor related code first. The code P0135 is for the heater circuit control in the front O2 Sensor. If you still have the old O2 sensor check the electrical connector on the old sensor two of the wires should have continuity to each other (this is the heater circuit, if none of the wires at the connector have continuity the sensor is in fact defective but they sometimes go "open only when hot operating conditions). The electrical harness itself gives problems and failure occurs bringing on the Service Engine Soon light. Ignition key on you should have power (12V) at the disconnected O2 sensor harness. The computer grounds the sensor heater circuit as required. The problem may have to be fixed by "ohming" out the harness wires until the fault is found. I suspect by fixing the P0135 problem your service light will stay out once reset. The knock sensor is labor intensive to replace.