J30 Emission Control device warning light

[gbridger]

My 94 J30, 135,000 miles, serviced regularly, has started displaying the yellow/orange emissions warning light on the right side of the dash, warning of the need to have these systems checked. I would believe it, except for the way it behaves. It started coming on about 10 days ago whle returning from a play at the University of Portland at night. As I entered I-5 it came on and stayed on for only a mile or two. Since then, it has appeared only 3 other times -- all while driving this same stretch of road to work in the morning; all for just a mile or two. It does not go on in the evening when I go through the same area.

First question -- what does this sensor measure?Second question -- what could be contained in the air to set it off?Third question -- is there an exorcist in the house?

[Q451990]

The Check Engine light monitors a number of sensors. You'll need to pull the codes from the ECU, or have it checked with Consult or another code reader. The service manual will walk you through the steps to check the codes if you want to do it yourself at the ECU. My guess is that the location where you're seeing the light coming on is less the issue than the number of minutes and time the car has warmed up since you started it. In the morning the car is cooler after sitting all night vs. at a parking lot in the sun at work.

A wild guess is that you have an O2 sensor hanging up during the warm up cycle, but I'd check the codes.

Heath

[gbridger]

I don't discount the need to get the electonic diagnosis (I don't have those machines in my garage, like I used to have the timing light, etc). But the curious part is that this does not occur on other mornings when I head off on a different route. Only on this route...

[maxnix]

Does the grade or acceleration vary, thus stressing the engine more?

If you get a Consult done at Infiniti of Beaverton, Eric is the senior tech.