Emissions - Proper Diesel Exhaust Fluid (DEF) Level
SI B 16 02 10
Fuel Supply Systems
March 2010
Technical Service
SUBJECT
Proper Diesel Exhaust Fluid (DEF) Level in SCR Reservoirs
MODEL
E70 and E90 with M57Y
SITUATION
When checking the levels of the SCR system with ISTA/D, the active tank level reading shows 66%.
CAUSE
2010 BMW 335d Sedan (E90) L6-3.0L DSL Turbo (M57Y) Page 285
Level measurement strategy of the SCR system
INFORMATION
The level sensors in the passive and active SCR tanks do not continuously measure the DEF level. There are defined measurement points in the level
sensor that the DDE control module uses to calculate the DEF level.
If the DEF level in the active tank (1) is above the full point (A) of the level sensor, the fluid level reading will be at 100% (full). Once the DEF level
is below the full point of the level sensor, but still above the warning point (B), the level reading will be 66%. The warning scenario displayed to the
customer will start to count down the mileage to "no start condition" when the DEF level is below the warning point (B), and above the empty point
(C) of the sensor.
RECOMMENDATION
Do not overfill the SCR system. Filling the tanks up to the top of their respective filler necks will cause the DEF to leak out of the tank's vent system,
and will possibly damage the tanks and internal components. All active and passive tanks are filled to the correct level at the factory. A tank level
reading of 66% on a new vehicle requires no further action.
Note:
Consult SI B16 03 10 if a low exhaust fluid warning is displayed in a new vehicle with low mileage (5,000 miles or less).
