Nissan Pulsar 2001: Check engine light

In late-December I was driving my 2001 Nissan Pulsar Q sedan up a gradual incline with the A/C on, and soon noticed that the "check engine" warning light had come on.

I slowed down and turned off the A/C, and the light disappeared after about a minute. A week later, I was driving up the same incline in hot conditions with the A/C off this time, and the light still came on, and went away soon after. The water, oil and coolant levels are all as they should be, so could this be perhaps a fault with the car's computer regarding its ability to detect potential engine issues?