The same mountainbike couldn't have explained it better. Sure, you're getting great gas mileage, but at what cost? Do you have any idea what it would cost if you, in fact, burned a hole in a piston? Trust me, it would be thousands of dollars, and I seriously doubt you want a repair bill like that.
You should NEVER ignore the SES light. It's an early warning system, meant to alert you to a developing problem while it's still simple and inexpensive to repair. You ignore the light at your peril, and the peril of your pocketbook.
The "meanings" you gave for whatever code is stored in your car's computer are vague, and unless you tell us the exact code we can only guess.
Take the car to a competent mechanic, let him or her diagnose the ACTUAL cause of the problem and fix it. Then you can drive on without worry.