W211 E220 cdi 2004..Reduced braking..start engine warning

[uk174]

Hi all,
My E220 CDi 2004 has a reduced braking..start engine warning in red when i unlock the car and this then disappears once the car is started.
I can see from some posts that this could be a sbc pump failure, however the car drives and brakes perfectly normal as far as I can tell.
My question is that could a low battery trigger this warning or is it better to just get it code read. Also if the pump has failed does anyone know the present cost of a replacement, used and new or whether or not they can be repaired.
The car has covered 101K with FSH..dealer/indie
Once again my thanks for all your help.

 

[pmcgsmurf]

Check your battery and aux battery.

I used to get the odd gremlin on mine so decided to change both batteries (hadn't been changed for years) and it's been fine ever since.

There's a lot of electronics in these car so a good battery is a must.

 

[uk174]

Just an update...finally managed to get the car code read on a star by a local indie and no stored fault was found for the SBC pump.
So I guess everthing seems to be pointing towards battery issues. Can any one tell me what the voltage should be on the aux battery and the main battery before and after cranking.?

 

[OneForTheRoad]

main can be anything , it depends on condition ,mine could drop to 11.2 v before i replaced the main battery , now its usually 12.2 v standing and 14.4 v with engine running ., my car is fitted with heavy duty alternator . unsure on small battery as i never check it ... i did charge it though when i was having your same issues.