2003 E320 computer message
 

Last weekend during 90 degree plus temperature outside, the computer message stated "Check Engine Oil- Reduce Oil Level" on two different days. The dealer checked the car and all computer systems and could not find any problem. Anybody have any ideas

Can you confirm if its overfilled? On my bosses E500 and E55 there is no dipstick to manually check the oil. Did you have the dealer use the dipstick and check the oil level? If not, I would have them do that, or try the check oil function that you access therough the steering wheel and the cluster.

The three most common causes, in my experience, for the "Reduce Oil Level" message are:

1. The oil level is, in fact overfull.
2. The Central Gateway (CGW) is incorrectly version coded. Either the engine type, or the national version should be checked.
3. The oil level/condition sensor is covered with sludge. This can cause the sensor to incorrectly report an overfull condition.

Question: How many miles on the Mobil 1 synthetic oil turns it into sludge.

2003 E320 computer message update
 

The dealer had the car for one day and checked oil level with a graduated dip stick and it measured 180MM. The oil was changed by the same dealer two weeks ago.