O2 Sensor Not Ready

[MaximaFrisco]

I have a 2001 Maxima GLE with 103K miles on it.. that is failing the emissions test due couple of sensors not ready state.

They are O2 Sensor and Catalyst.

I have told by the mechanic that I need to drive some 30-40 miles to get it to ready state. But, after 400 miles,(atleast 4 times 40 miles each on Freeways), I still have the problem.

Should I suspect any other problem like O2 sensor is actually bad or Some onboard computer issue ?

I would really appreciate any response on this..

[Sawyer_]

I keep getting P0140 on my 2000 Maxima Every now and then.
According to my mechanic, the O2 sensor is working OK, but he suspected a leak in the front exhaust, somewhere before the catalyst converter.

Check your actual codes and determine if a possible leak in the exhaust system could be the reason for your failure.

[MaximaFrisco]

Thank you. I will get it checked. Thanks for the reply

[017hnoor]

I have told by the mechanic that I need to drive some 30-40 miles to get it to ready state. But, after 400 miles,(atleast 4 times 40 miles each on Freeways), I still have the problem.

[NutriaforBreakfast]

The 40 mile drive idea is to get the CAT very hot to process the NOX
(Nitrogen Oxide) gas. The test would show low NOX and then you get
your inspection sticket.

Your O2 sensors might be so old that they do not provide quick enough
readings to your computer.

or

On my 95, there are two O2 sensors. If the readings BETWEEN the O2
sensors are not within tolerances, I will get a check engine light.

I noticed it was just as expensive to check the O2 sensors as to buy
new ones so i just bought new ones. If you have not changed them
before 103,000 miles, i would guess you need new ones. I recommend
Bosch or OEM from Nissan.

[MaximaFrisco]

Thank you. The O2 sensors went bad some 4 years ago and I had them replaced with OEM.