I have a reoccurring problem with one of my red dash warning lights. It comes on randomly. If I open up the throttle the light shuts off or if I shut down the motor and restart it the light stays off. The Merc Scan tool show all systems are working good at al RPMs . Someone mentioned an 02 sensor but merc says the 500efi has no 02 sensor.
Any advice?

2001 Twin Step 500efi 300hours

Could be a short or bad ground on one of the sensors triggering the warning light.

My 00 Mystique with 500 efis have one of the same sensors that comes on every time the motor warms up and stays on. I was also told it might be an 02 sensor.

Bmanafort- I called Bud at Cigarette to help narrow down the problem. Water Temp, Oil Temp, Oil pressure, Drive fluid level are all linked to the light. In my case my water temp switch was "gummed up" and I believe it's fixed now. Yours could be the same. I'm thinking maybe we should replace them all.. say every 200 hours. Cigarette told me that 9 time out of ten when the light comes on - its a sensor acting up and thats the same thing we find with Harley-Davidson warning light system-sensors seem to be the weakest link-

thanks for the info