LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Mercedes Benz >> 2022 >> E450 4Matic All-Terrain >> Repair and Diagnosis >> Engine Performance >> Ignition System >> Electrical System -- Engine -- 213 Chassis >> Testing & Repair >> Remove/Install Integrated Starter Alternator Control Unit - AR15.40-P-0004MSA
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Remove/Install Integrated Starter Alternator Control Unit - AR15.40-P-0004MSA

Engine 256.9 in model 213, 238, 257, 290 

MODIFICATION NOTES

07.05.2019 Phase bolt on inverter   BA15.40-P-1008-02MRT
31.03.2020 Screw, holder for wiring harness (integrated starter alternator/refrigerant compressor/transmission) to crankcase   BA15.40-P-1014-02MRT
04.07.2023 Bolt, terminal box cover to starter-alternator control unit   BA15.40-P-1004-02MRT
Fig 1: Integrated Starter Alternator Control Unit Components Location - Engine 256.9 In Model 213
G16163053Courtesy of MERCEDES-BENZ USA
G16163054Courtesy of MERCEDES-BENZ USA
WARNING Risk of injury  to skin and eyes suffering scalding from contact with hot coolant spray. Risk of poisoning  from swallowing coolant. Do not open cooling system unless coolant temperature is below 90°C. Open cap slowly and release the overpressure. Do not pour coolant into beverage containers.
Wear protective gloves, protective clothing and safety glasses.		 AS20.00-Z-0001-01A
CAUTION Risk of injury  caused by scraping or cutting body parts on sharp vehicle parts Always wear protective gloves when working on or near sharp and non-deburred vehicle parts.
Deburr repair panels.		 AS00.00-Z-0017-01A
Notice Notes on coolant   AH20.00-P-2080-01KOA
Notice Information on preventing damage to electronic components due to electrostatic discharge   AH54.00-P-0001-01A
Notice Notes on avoiding damage through contamination and foreign objects   AH00.00-P-5000-01A
  Notes on safety-relevant components   AH00.00-Z-0019-01A
REMOVINGINSTALLING Remove/install     
1 Disconnect ground line from battery. Engine 256.9 in model 213 AR54.10-P-0003LW
    Engine 256.9 in model 238 AR54.10-P-0003LWO
    Engine 256.9 in model 257, 290 AR54.10-P-0003FR
2 Drain off low-temperature circuit coolant. INSTALLATION IMPORTANT Only install lower engine compartment lining after leak test. AR09.41-P-6834MSA
3.1 Remove the catalytic converter. Engine 256.9 in model 213, 238
up to model year 2020
Engine 256.9 in model 257
except code 961 (Exhaust system with OPF, generation 2.0)
except code 999 (Exhaust system with OPF, generation 3.0)
Engine 256.9 in model 290
except code 961 (Exhaust system with OPF, generation 2.0)
except code 999 (Exhaust system with OPF, generation 3.0)		 AR49.20-P-0100MSA
3.2 Remove exhaust gas aftertreatment unit. Engine 256.9 in model 213, 238
as of model year 2020
Engine 256.9 in model 257, 290
with code 961 (Exhaust system with OPF, generation 2.0)
Engine 256.9 in model 257, 290
with code 999 (Exhaust system with OPF, generation 3.0)		  
    Engine 256.9 in model 213, 238
as of model year 2020		 AR49.20-P-1500MSA
    Engine 256.9 in model 257
with code 961 (Exhaust system with OPF, generation 2.0)
Engine 256.9 in model 257
with code 999 (Exhaust system with OPF, generation 3.0)
Engine 256.9 in model 290
with code 961 (Exhaust system with OPF, generation 2.0)
Engine 256.9 in model 290
with code 999 (Exhaust system with OPF, generation 3.0)		 AR49.20-P-1500SA
4 Remove heat shield above starter-alternator control unit (N129). TORQUE SPECIFICATION Screw, heat shield to crankcase/catalytic converter bracket/engine mount heat shield *BA22.10-P-1004-02A 
5 Remove coolant lines (1, 2) from the starter-alternator control unit (N129).   AR20.20-P-7441-01RQ
    SPECIAL TOOL Set of protective covers Fig 2
6 Remove coolant line (2) from timing case cover and place to one side.   AR20.20-P-7441-01RQ
    TORQUE SPECIFICATION Bolt, coolant return line to timing case *BA15.40-P-1009-02MRT 
    SPECIAL TOOL Set of protective covers Fig 2
7 Remove coolant line (1) from crankcase and place to one side.   AR20.20-P-7441-01RQ
    TORQUE SPECIFICATION Bolt, coolant feed pipe to crankcase *BA15.40-P-1010-02MRT 
    SPECIAL TOOL Set of protective covers Fig 2
8 Release and disconnect electrical connector (4).    
9 Open cover caps of the electric lines, unscrew nuts (3) and remove electric lines from the starter-alternator control unit (N129). TORQUE SPECIFICATION Nut, circuit 40/41 to starter-alternator control unit *BA15.40-P-1011-02MRT 
10 Remove bracket (7) and place 48 V wiring harness (5) to one side. TORQUE SPECIFICATION Bolt, holder for wiring harness (integrated starter alternator/refrigerant compressor/transmission) to crankcase *BA15.40-P-1014-02MRT 
    TORQUE SPECIFICATION M6x1 *BA00.10-P-1002-04A 
11 Remove bracket (6). TORQUE SPECIFICATION Nut/bolt, holder for catalytic converter to crankcase *BA49.10-P-1007-02P 
12 Remove screws (10) and remove cap (11). INSTALLATION IMPORTANT Replace seal.  
    TORQUE SPECIFICATION Bolt, terminal box cover to starter-alternator control unit *BA15.40-P-1004-02MRT 
13 Release and disconnect electrical connector (12). NOTES Press release mechanism in direction of arrow (A).
Otherwise, damage to the starter-alternator control unit (N129) will occur.		  
14 Unscrew screws (13). TORQUE SPECIFICATION Phase bolt on inverter *BA15.40-P-1008-02MRT 
15 Remove screws (14) and remove starter-alternator control unit (N129). INSTALLATION IMPORTANT Replace seal.  
    TORQUE SPECIFICATION Bolt, starter-alternator control unit to crankcase/timing case *BA15.40-P-1005-02MRT 
16 Install in the reverse order.    
17 Read out and delete fault memory.    
REFER TO SELF-DIAGNOSTIC SYSTEMS   Engine 256.9 in model 213 AD00.00-P-2000-04B
REFER TO SELF-DIAGNOSTIC SYSTEMS   Engine 256.9 in model 238 AD00.00-P-2000-06LWO
REFER TO SELF-DIAGNOSTIC SYSTEMS   Engine 256.9 in model 257, 290 AD00.00-P-2000-06FR
WARNING Risk of accident  from vehicle starting off by itself when engine running. Risk of injury  (bruises and burns) resulting from working on the engine while it is being started or when it is running. Secure vehicle to prevent it from starting off by itself. Wear closed and snug-fitting work clothes. Do not touch hot or rotating parts. AS00.00-Z-0005-01A
18 Carry out engine test run and check engine for proper operation and leak tightness.    
METRIC SCREWS/BOLTS AND NUTS AS PER MBN 10 105, 10 143

Number Designation 8.8 10.9
BA00.10-P-1002-04A M6*1 Nm 9 13
STARTER-ALTERNATOR

Number Designation Engine 256
BA15.40-P-1004-02MRT Bolt, terminal box cover to starter-alternator control unit Nm 11
STARTER-ALTERNATOR

Number Designation Engine 256
BA15.40-P-1005-02MRT Bolt, starter-alternator control unit to crankcase/timing case Nm 8
STARTER-ALTERNATOR

Number Designation Engine 256
BA15.40-P-1008-02MRT Phase bolt on inverter Nm 11
STARTER-ALTERNATOR

Number Designation Engine 256
BA15.40-P-1009-02MRT Bolt, coolant return line to timing case Nm 8
STARTER-ALTERNATOR

Number Designation Engine 256
BA15.40-P-1010-02MRT Bolt, coolant feed pipe to crankcase Nm 8
STARTER-ALTERNATOR

Number Designation Engine 256
BA15.40-P-1011-02MRT Nut, circuit 40/41 to starter-alternator control unit Nm 16
STARTER-ALTERNATOR

Number Designation Engine 256
BA15.40-P-1014-02MRT Bolt, holder for wiring harness (integrated starter alternator/refrigerant compressor/transmission) to crankcase Nm 12
ENGINE SUPPORT (ENGINE SIDE)

Number Designation Engine 256
BA22.10-P-1004-02A Screw, heat shield to crankcase/catalytic converter bracket/engine mount heat shield Nm 8
EXHAUST SYSTEM

Number Designation Model 213 with engine 256 Model 238 with engine 256
BA49.10-P-1007-02P Nut/bolt, holder for catalytic converter to crankcase Nm 20 20
EXHAUST SYSTEM

Number Designation Model 257 with engine 256 Model 290 with engine 256
BA49.10-P-1007-02P Nut/bolt, holder for catalytic converter to crankcase Nm 20 20
Fig 2: Identifying Set Of Protective Covers (001 589 11 91 00)
G16163055Courtesy of MERCEDES-BENZ USA
scientia non olet · About LEMON Manuals