Most but *not* all CHECK ENGINE flags are emission-related.
A failing/old gas-cap, or even screwing it on cock-eyed can cause a CHECK ENGINE light on these cars.
A failing fuel-filter was causing a lean-condition on mine (C36), so at 80K miles, if you don't know when the fuel-filter or gas-cap was replaced, I'd change them out now and use this as your baseline. O2-sensors (you have two of them) should IMHO also be changed out every 100K miles.
Best of luck,