Good evening, I have a Nissan Maxima 2002, in fairly good condition, the maintenance always have been done on schedule... We have been having troubles with the check engine soon light in my car since last year, (is an orange light).

The code indicated the O2 sensor needed to be replaced or the fuel cap has to be well closed …
The head of the fuel tank is rusty but I can the fuel cap is not lose and it is well closed

The car have been performing fairly good, I do not feel any difference in the drive. My questions are: What should be done now? the mechanic told me there are 2 O2 sensors and he do not know which one needs to be replaced and should we get the OEM parts or after market?

I hope you can guide me with this, thanks in advance for the help you can give me

 

Please give us the actual code.

 

go to autozone and get the car scanned for free. They'll tell you the code(s) that are causing the Check engine light to come on.
Find the code on this schematic ( if it is an o2 sensor related issue.)
http://forums.maxima.org/5th-generat...bs-inside.html

and call it a day...

 

Or just read the codes yourself with the "pedal dance".



...but STOP at step 5. Once the MIL starts blinking is when you start writing. Similar to morse code is how the codes are read out.

e.g., P1234 and P4321 in sequence would be:
flash
pause
flash-flash
pause
flash-flash-flash
pause
flash-flash-flash-flash

BIG PAUSE

flash-flash-flash-flash
pause
flash-flash-flash
pause
flash-flash
pause
flash


10 flashes is a zero. The separation of digits' pause is about 1 second. The separation of codes' pause is about 2 seconds.

 

see sig for info on codes related to O2 sensors

 

there are 4 o2 sensors on the car.

try to stick with oem as they last a bit longer or at least the direct replacement aftermarket sensors.
Do not get the universal type, you might have problems with them.