sounds like to me one of the abs sensors may need cleaning or faulty.
Have a similar problem with my forester 1999.
The tail light fuse panel for the Subaru Impreza WRX located in the fuse box.
If the engine oil level is at the full mark, the light is not suppose to come on when driving.
Replace the bulb
If the ABS and brake light are coming on while driving, this is an indicator that it is time to get your brakes checked and replaced. If not, the brakes will wear out causing you to not be able to stop.
Purchase a new one
To change the park light on a Subaru Impreza prop the trunk lid open and locate the taillight housing. Remove the plastic cover and the bulbs for the parking lights. Replace the bulbs.
Breaking a light stick is not a chemical in and of its self, but the subsequent process that produces light is.
why the engine light of my subaru came on after i washed the engine
check your Oil..perhaps it's too low.
If the light is red first apply the brakes then shift into neutral. If the light is green don't shift, just continue through. If the light is yellow you will have to decide for yourself depending on the situation which of the above to do.
the car usually has a light on and the car is to alert all other cars that there is a big lorry coming