# CEL On..O2/Knock sensors reported



## sanjaybala (Sep 8, 2004)

I got my ECU/CEL light on a few days ago on my 95 Altima GXE. The car is driving perfectly fine(so far no problems with bad mileage either). After reading similar posts in this forum, I took my car to an Autozone shop for a free ECU code analysis. They told me it was reporting the Knock Sensor and O2 Sensor being awry. They have a Bosch O2 sensor for about 39$ and a Knock sensor for about 170$. Am I right in assuming that the Knock sensor code is thrown in as a precautionary measure and that I should first only replace the O2 sensor, clear the codes and see if the light comes back on for the Knock sensor?
Can I buy the O2 sensor from Autozone and change it myself? I havent done any repairs on my car myself in the past(have had one only for the past 5 months !).
I want to add that a few weeks ago I got my fuel system and fuel injector cleaned at Valvoline and I saw a lot of smoke when they were finishing. Would this have damaged the O2 sensor?
Any help/pointers on changing the O2 sensor will be appreciated. Thanks.
Sanjay.


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## Darktide (Jul 29, 2004)

first off. on the a fuel injection system cleaning... you get a SHIT LOAD of white smoke. It shouldn't hurt a thing (I only say that because Valvoline is nation-wide and well known therefore they shouldn't be using chemicals that'll damage anything). On ward. Oxygen sensors are a breeze. There is a special socket you can get to take them out (has a side missing so that the wiring has a place to go) or you can use a wrench (if you can fit it). In all honesty I would just replace the O2 sensor first like you said. Go for the least painful part of your problems. Your reasoning for clearing the codes after changing the O2 sensors is also good. I would follow that idea (and even though they say don't change an O2 sensor unless its throwing codes it can't hurt anyway). I wish you the best of luck with it :fluffy:


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## sanjaybala (Sep 8, 2004)

Darktide said:


> In all honesty I would just replace the O2 sensor first like you said. Go for the least painful part of your problems. Your reasoning for clearing the codes after changing the O2 sensors is also good. I would follow that idea (and even though they say don't change an O2 sensor unless its throwing codes it can't hurt anyway). I wish you the best of luck with it :fluffy:


Thanks for that. Can I go in for the Bosch OEM O2 sensor which retails for abt 40$? The reason being I asked a few mechanics around here for a quote and they all recommended the dealer OEM part which is like 150$ !! They said I will screw up my car if I put in the Bosch OEM one. Are they just ripping me off for a higer margin or should I be worried?

Sanjay.


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