B180217

TIS Service Bulletin
Page 1 of 1
SI B18 02 17
Exhaust Systems
December 2017
Technical Service
DIAGNOSING SELECTIVE CATALYST REDUCTION (SCR)
EFFICIENCY FAULTS
MODEL
E90 (335d)
E70 (X5 xDrive35d)
SITUATION
The Service Engine Soon light is on. The mileage countdown warning to a no start condition is displayed in the
Control Display for incorrect exhaust fluid added. One or more of the following fault codes are stored in the
DDE:
M57Y:
z
41F9 SCR system: System error and poor urea/water mixture quality detected
z
474C SCR system, warning and deactivation scenario: Warning level 1
z
4748 SCR system, warning and deactivation scenario: Warning stage 2
z
4746 SCR system, warning and deactivation scenario: Warning stage 3 (maximum range reached)
z
4D08 SCR system, warning and deactivation scenario: Warning stage (maximum range reached, no
engine start possible)
z
4D16 SCR system, efficiency (model years 2009 – 2012)
z
42FC SCR exhaust emission system, efficiency (model year 2013 E70)
z
4D18 SCR system, efficiency (model year 2013 E70)
CAUSE
The SCR system is not efficiently converting NOx.
PROCEDURE
Follow the troubleshooting attachment for enhanced diagnosis of the SCR system.
WARRANTY INFORMATION
Not Applicable
ATTACHMENTS
View PDF attachment B18 02 17 SCR Diagnosis.
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December 2017
PRELIMINARY WORK
•
Work through all other fault codes stored in the DDE (EGR, fuel/air, boost control, SCR
tanks, etc.). Other faults stored in the DDE not related to SCR can affect the NOx levels in
the exhaust.
•
Check vehicle service history for previous repairs/ parts replacement. Do not repeatedly
replace parts based off the SCR system diagnosis final report (Example: Test plan states
to continually replace an NOx sensor that is known to be a good part).
•
Confirm the engine runs at operating temperature. An engine running cooler than
specified (thermostat jammed open) will affect EGR and fuel injection rates which will
affect NOx levels that the SCR system has to convert.
The engine temperature can be monitored through the KOMBI test functions.
o With KL15 on press and hold down the reset button in the instrument cluster for 10
seconds.
o Press the reset button to scroll to test step 19 and unlock the instrument cluster
(the unlock code is the sum of the last 5 digits of the VIN – example: VIN XY12345
(1+2+3+4+5 = 15).
•
o Scroll through the test steps again
to test step 7 (engine operating
temp).
•
•
Drive the vehicle and monitor the engine temperature. The coolant thermostat should
open at 88°C (±2°C). NOTE: Do not leave the engine idling in the shop to monitor the
engine coolant temperature. Only checking while driving (air passing through the radiator)
will give an accurate reading of the engine operating temp.
Replace the engine thermostat if necessary.
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December 2017
CHECKING THE DEF MIXER (E90 and E70 with the M57Y)
Ensure the mixers are pointing correctly in the exhaust stream for proper dispersion of
ammonia into the SCR cat.
•
The retaining tabs (1) for the E90
mixer point towards the tailpipe.
•
The retaining tabs (1) for the E70
mixer point towards the engine.
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December 2017
•
The E90 mixer (1) is shorter than
the mixer for the E70 (2).
The mixers are model specific and designed to disperse the ammonia into the exhaust
path correctly. If necessary, remove the mixer for inspection and proper fitment. The
E90 mixer can fit into the E70 exhaust system. Ensure the correct mixer is installed
and is facing in the correct direction.
•
•
Inspect the fins on the mixer. If
the fins are split (1) the mixer
needs to be replaced.
Replace the mixer with P/N 18 30
8 513 445 (E70) or P/N 18 30 8
512 438 (E90).
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December 2017
•
Check for contamination, damage
to the fins or DEF build-up on the
mixer (1). DEF build-up can
washed away with water.
CHECKING DEF CONCETRATION and THE METERING VALVE
•
•
•
Check the DEF with a calibrated
refractomer (SI B04 19 11). The
concentration of urea must be
within 31.8 - 33.3%.
If the DEF concentration is below or above the specified range the DEF needs to
be fully drained and refilled with fresh DEF.
Vehicles that are constantly having top offs of the active tank will may end up with
degraded DEF in the passive tank. Once there is a transfer of DEF from passive to
active the degraded fluid will contaminate the active tank (vehicle may return for a
repeat visit where the system was operating as designed at last repair). Check the
DEF concentration at the passive tank and drain/replace if necessary)
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December 2017
•
If the concentration is within specification: Check that the DEF tanks are not
empty (at least ¼ full). Top off if necessary
•
The metering valve needs to be removed when checking the dosing amount
during the first test step of the SCR System Test (ABL-DITAT1361_SCR_SYS_M57_2-SCR exhaust emission system test – V.2).
• Check the metering valve for any
DEF build-up (1) during this test.
Clean off build-up with water.
• Check the spray pattern of the metering valve when performing the quantity
measurement.
• Check the port for the metering valve in the exhaust for any crystalized DEF buildup.
•
Any blockage in the exhaust (1)
will compromise the spray of DEF
and will also absorb DEF which
will decrease the amount of
ammonia entering the SCR cat.
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December 2017
CHECKING THE NOx SENSORS
•
•
Remove the NOx sensors from the exhaust and check the tips for contamination
(excessive urea/oil). Reinstall if the ends are clean.
Follow Test Plan ABL-DIT-B1365_D7SCRNOX-SCR: Nitrogen oxide sensors
(NOx sensors)-V.13 to check for updated NOx sensors.
•
ISTA will recognize the newest
NOx sensor part number available.
Replace the NOx sensor/s if the
test plan indicates an old part
number.
•
Latest Part Numbers for NOx
sensors:
E70 and E90 pre:13 62 8 589 846
E90 post :13 62 8 589 845
E70 post :13 62 8 589 844
SCR CATALYST
Do not perform an SCR catalyst reset with Test Plan ABL-DITB1365_D7USANAB-SCR system: Adjustment – V.20 (replacement of the SCR
cat) unless the SCR cat has been replaced.
To reset SRC catalyst aging factor back to the current vehicle mileage do the
following:
•
•
•
•
•
•
Run Test Plan ABL-DIT-B1365_D7USANAB-SCR system: Adjustment –
V.20
System: SCR catalytic converter Selection:
Select 2 Carry out SCR adjustments.
Select 4 Engine control unit
Select 2 A new control unit was already fitted. Date from the old control unit is
not to be rescued.
The current mileage gets transferred automatically into the DDE.
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December 2017
PERFORMING THE CONDITIONING RUN
A conditioning run has to be performed if one or more of the following fault codes are
stored:
•
•
•
•
•
41F9 SCR system: System error and poor urea/water mixture quality detected
474C SCR system, warning and deactivation scenario: Warning level 1
4748 SCR system, warning and deactivation scenario: Warning stage 2
4746 SCR system, warning and deactivation scenario: Warning stage 3
(maximum range reached)
4D08 SCR system, warning and deactivation scenario: Warning stage
(maximum range reached, no engine start possible)
These faults cannot be cleared until the DDE has monitored a successful SCR
conditioning run (Correct DEF and SCR efficiency)
DO NOT CLEAR FAULTS
• Check the DEF filling level and top up. Turn on the ignition and wait 3 minutes.
The Check Control message will disappear if the cause was missing DEF in the
active tank.
• Check if the active tank is frozen; if so, let it thaw.
• Check whether other fault codes relating to the SCR system are stored and
rectify them.
• Check the quality of the DEF and drain/replace if necessary.
In case of further stored SCR faults, perform the following steps:
• Rectify SCR faults.
• Reset the SCR adaptations (long-term adaptation factor only).
• Request a forced diesel particulate filter regeneration. Follow Test Plan ABLDIT-B1363_D7CSFREG. Select Request regeneration (first selection).
• Drive the vehicle until the Check Control message for the switch-off scenario in
the KOMBI goes out. The minimum duration for the drive is 20 minutes at
approximately 60 - 90 km/h (45 - 60 mph) but could take up to one hour.
NOTE: The vehicle may also be driven when the mileage countdown range is
insufficient for the test drive (mileage range has reached 0). Only the engine start
will be prevented. Do not turn off the engine!
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December 2017
There is a one-time reset available through ISTA to reset the count-down to 50
miles. Follow test steps in Test Plan ABL-WAR-B1365_D7SCRRST – SCR
reset – V.3
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