check engine.....

[mad scientist]

Really need some help with this problem! I've tuned up the car and even replaced the o2 sensor and even tried to reset the computer and its still on ! What can it be? It runs fine.... 1992 nissan 240sx LE 5 speed dohc hatchback.

[duffman1278]

Check the codes on the ECM instead of just trying to reset it.

[s13 @ fullboost]

and if you check and it says all clear then I will bet you anything you have the dial in diagnostic mode and that's why its staying on. So check to make sure that its in normal operation mode.