If it's as intuitive as the check engine lights we have today, it could mean anything from a slightly dirty plasma conduit to 'the warp core is mid-breach'.

Eject the warp core!

The "check dilithium chamber" light has been on since Starbase 34.

Just imagining Tom Paris rocking up, shoving Geordie out of the way, and starting a lecture on 20th century earth automobiles.

The ship has been rearranged in design with both warp core engines aimed in two different angles for maximum efficiency.

I think it means you need to reverse the polarity of something. Or do something with auxillary power.

Geordi: It's nothing to worry about really, Data. If we were on the original NCC-1701, this would be a bigger deal, but on modern models like ours, we can probably safely ignore this for a while.

Better eject the warp core immediately.

If it's anything like my vehicle, they forgot to securely tighten the gas dilithium cap after refueling.

the mass tachyon flow sensor has been acting up again

"... and for some reason the ODB 2 connector is under your console on the bridge, Data. You have to take the ashtray out to get to it." - Geordie, probably

It's clearly an experimental Romulan warship.

Time to realign something or reverse some polarity somewhere.