You need to read the code(s) set to begin to make repairs. Depending on what model and year your vehicle is you probably have more than one O2 sensor. Many auto parts stores will read your codes for free in hopes you will purchase the parts from them to correct your problem.
There is another problem. see related questions.
check fuel pressure regulator
Did you reset the light? I don't know what gasket you changed, but undoubtedly that was not the problem. The check engine light comes on when there is a problem with the emissions system.
Check to see if the wiring is damaged.
* It could be a faulty check engine light or a light sensor problem . There's probably not a problem with the engine at all just the faulty sensor light problem most likely. * ----------------------------------------------------------------------------------------------------If your check engine light stays on with the engine running , a malfunction with the emission control system has been detected. Have your vehicle scanned for any trouble codes in order to diagnose and repair the problem. ( I had a check engine light come on at 35000 miles - in my case it turned out to be the DPFE sensor )
The check engine light will illuminate with a code(s) directing which O2 sensor is bad.
If the same code resets, then you have a wiring problem.
Do you have a check engine light. I have had problems with my 01 Lanos and the check engine light came on and it was the oxygen sensor so that may be your problem
Need to know what code(s) were set and which O2 sensor you changed in order to help you.
Check the engine sensors. I changed all the engine sensors on my 1996 Dodge Ram Van and it vehicle only started when I changed the Flywhel sensor on the bellhousing and it was also the cheepest sensor to buy. My auto mechanic scanned the on board computer but this did not show up the problem sensor. he had a spate of Chrysler group vehicles in with this same problem and it turned out to be the Flywheel sensor and for some reason Chrysler do not put this sensor into the on board computer checking system and did not show a fault code on the OBD.
changed battery engine light stays on
Be sure to check the wires going to the IAT sensor. Nissan used cheap wiring for this and it usually breaks. The problem is the wires constantly flex when the engine moves.