Hello All,

I have few concerns with my Nissan Altima 2000 GXE...
The check engine light has started glowing and then I took it to Autozone and they told me the code is P0420. They told me to change the Catalytic Converter.
I went to Advance Auto parts to confirm (just to double check) and they asked me to change the O2 sensors.

I would like to mention that my temperature gauge is not working properly. It fluctuates up and down. Please suggest me what is the right thing to do now... Do you think the code showed up due to the bad temperature gauge or is it O2 sensor related??

Thanks so much for your help... Many Thanks in advance...

Bobby

P0420 relates to the catalytic converter functioning below it's designed threshold. The Powertrain Control Module (PCM) uses O2 sensor data to make the determination, so have a qualified technician diagnose the sensors, just in case they are providing faulty readings.
As for the temp gauge fluctuation, that is unrelated to the trouble code, but still needs diagnosed. Some movement is normal.
Good luck, Bobby. I hope this helps.