MY 2001 INFINITI QX4 KEEPS SAYING SERVICE SOON
First off, make sure that the gas cap is tightened beyond three clicks. If it is and has been then there are many things that could be causing the light to come on. But let me start by assuring you that it is not something that requires immediate attention. The sole purpose of the service engine light is to detect malfunctions of emissions related components. If the gas cap isn't tight, the computer system detects an incorrect amount of pressure inside the tank due to vapor leaking out of the filler neck. If the cap is tightened after a period of time the computer detects the right pressure and the light will go off. However, on QX4's the most common cause of the light is oxygen sensors, or cam and crank position sensors, and finally intake valve timing control sensors or solenoids. O2 sensors measure the amount of oxygen in the exhaust gas. Normally I have seen that in damp and wet conditions these sensors are more likely to intermittenly give false readings. That being said, although the SES light is not an emergency situation, it will need to be addressed at some point, as the Engine control module takes the readings from these various sensors and automatically adjusts things like idle control, and air fuel mixture ratio, and eventually will to some point affect the performance of the vehicle. I have seen folks drive 100K miles with a service engine light on, so if you don't want to spend a 200 or so dollars right away, I would take the car to autozone, have the codes retrieved, and report back to this forum, at that point I would be able to advise you a little further. But more than likely you could continue driving the car without any driveablility issues.
