On starting the SL (R230 model), I get a message 'Reduced Braking Effect, Start Engine'. Someone has suggested that I get this message because the battery in the boot is not fully charged. Could this be right?
The manual is often helpful when trying to understand what the car is telling you.
This can happen even if everything is fine but your battery just runs out of power when the engine is off. But if your battery (two batteries on an R230) is bad, you get the message more often.
I quite often got the same message on my E class ( w211 ) but it would go away as soon as the engine was started. This would usually be after the car had been sitting for a few days without running. I never bothered to change the battery as it didn't interfere with starting the car or driving.