Mercedes W246 (w242) is a series of B-class compact cars of the Mercedes-Benz brand that was produced in 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019 with the designation B160, B180 CDI, B200, B220 4MATIC, B250 . During this time, the model has been restyled. In our article you will find a description of the Mercedes w246 fuses and relays with box diagrams, photo examples of performance and locations. Separately, we single out the cigarette lighter fuses.
The purpose of the fuses and relays may differ from the one shown and depends on the year of manufacture and the level of equipment of your car.
Passenger compartment
In the cabin, the main fuse and relay box is located under the panel, on the passenger side under a protective cover.
Diagram
Assignment
21 | 150A Auxiliary electric heater (vehicles with diesel engine) |
22 | 200A ECO start-stop auxiliary battery relay |
23 | 30A Front left door control unit |
24 | 30A Front right door control unit |
25 | 30A SAM control unit |
26 | 10A ECO start-stop auxiliary battery cable termination |
27 | 30A Engine compartment fuse and relay module |
28 | 5A Electric Drive (W242): Thermal management unit |
29 | 15A Trailer socket (up to 02.11.2014) |
Trailer detection control unit (from 03.11.2014) | |
30 | 5A Trailer detection control unit |
31 | 5A AWD control unit |
32 | 5A Signals from the steering column electronic module control unit |
33 | 5A Audio module/COMAND system control panel |
34 | 7.5A Climate control panel |
35 | 40A Heated rear window |
36 | 7.5A Driver’s seat control unit |
Lumbar adjustment control unit for driver’s seat | |
37 | 7.5A Audio module / COMAND system display |
38 | 7.5A Supplemental Restraint System control unit |
39 | 10A Ceiling Control Panel |
40 | 15A Transmission control unit (engine 651) |
5A Electric Drive (W242): Transmission control unit | |
41 | 30A Panoramic sliding sunroof control module |
42 | 5A Audio module |
COMAND control module | |
25A Audio module | |
43 | 5A Parking assistance control unit |
44 | 40A Front left seat belt reversible pretensioner |
45 | 40A Front right seat belt reversible pretensioner |
46 | 7.5A Front passenger seat control unit |
Lumbar support adjustment control unit for front passenger seat | |
47 | 7.5A Navigation module |
25A Adaptive damping system control unit | |
48 | Reserve |
49 | 7.5A Drive Kit Control Unit for iPhone |
5A Fan motor COMAND | |
50 | 5A Camera cover control box |
51 | Reserve |
52 | 30A Parking lock actuator signal |
53 | Reserve |
54 | Reserve |
55 | 5A Telecom Services Communication Module |
Control unit KEYLESS-GO | |
56 | 10A Signals from the steering column electronic module control unit |
57 | 30A Multifunction control unit for special vehicle |
7.5A Multifunction control unit for special vehicle | |
5A Terminal 87 relay Park lock actuator | |
58 | 30A Special vehicle fuse box |
59 | 30A Front passenger seat control unit |
60 | 30A Driver’s seat control unit |
61 | 40A Speaker amplifier control unit |
62 | 20A Electric steering lock control unit (711 transmission) |
63 | 25A Fuel pump control unit |
5A Electric Drive (W242): Transmission Interface Control Unit | |
64 | Control unit “Electronic Toll Collection” |
DSRC Toll Communication Control Unit | |
65 | 5A Glove box light |
66 | 15A Special vehicle fuse box |
5A Special vehicle interface | |
67 | Reserve |
68 | Reserve |
69 | Reserve |
70 | 25A Rear center console socket |
71 | 25A Socket in trunk |
72 | 25A Cigarette lighter with front ashtray illumination |
Socket in salon | |
73 | 30A Electric parking brake control unit |
74 | 30A Electric parking brake control unit |
75 | 20A Trailer recognition control unit |
5A Electric Drive (W242): Battery management system control unit | |
76 | 25A Trailer recognition control unit |
5A Electric Drive (W242): Parking lock control unit | |
77 | 25A Trailer recognition control unit |
78 | 40A Tailgate/Tailgate control unit |
Special Vehicle Fuse Block | |
79 | 40A SAM control unit |
80 | 40A SAM control unit |
81 | 40A Fan regulator |
82 | 10A Ceiling Control Panel |
83 | 7.5A Electronic ignition lock control unit |
84 | 5A Upper control box |
85 | 5A EDW/Tow protection/Interior monitor control unit |
86 | 5A FM, AM and ZV Antenna Amplifier |
Antenna amplifier/compensator for mobile communication (from 06/01/2016) | |
87 | 10A Diagnostic connector |
88 | 10A Instrument cluster |
89 | 5A Outdoor lighting switch |
90 | 5A Intelligent radar sensor in rear bumper, left |
Intelligent radar sensor in the right rear bumper | |
91 | 5A Pedal control sensor |
Footwell lighting switch | |
Electric Drive (W242): Battery management system control unit | |
92 | 5A Fuel pump control unit |
Electric Drive (W242): Transmission interface control unit | |
93 | 5A Electric parking brake control unit |
94 | 7.5A Supplemental Restraint System control unit |
95 | 7.5A Occupancy recognition and AKSE, front passenger seat |
Weight Sensing System control unit | |
96 | 15A Tailgate wiper motor |
97 | 5A Mobile phone electrical plug |
98 | 5A SAM control unit |
99 | 5A Tire pressure monitoring control unit |
100 | 5A DIRECT SELECT interface (engine 133) |
101 | 10A AWD control unit |
102 | 5A Radio remote control receiver for auxiliary heater |
Transmission control unit (Electric Drive (W242)) | |
Drive mode control unit (AMG, from 09/01/2015) | |
Antenna switch for telephone and auxiliary heater (from 06/01/2016) | |
103 | 5A Emergency call system control unit |
Telecom Services Communication Module | |
HERMES control unit | |
104 | 5A Multimedia interface control unit |
Media Connectivity Module | |
105 | 5A Digital audio broadcasting control unit |
Satellite Digital Audio Radio (SDAR) control unit | |
7.5A Tuner module | |
106 | 5A Multifunction camera |
107 | 5A Digital TV Tuner |
108 | 5A Rear view camera |
7.5A Rear view camera (from 06/01/2016) | |
109 | 20A Electrical plug socket for cargo |
110 | 30A Audio module |
COMAND control module | |
Motorsound control unit | |
Relay | |
A | Relay terminal 15 |
B | Rear window wiper relay |
C | Relay terminal 15R2 |
D | Heated rear window relay |
E | Relay terminal 15R1 |
F | Relay terminal 30g |
G | Electric Drive (W242): Terminal 87 relay Park lock actuator |
Fuses numbered 70, 71 and 72 are responsible for the cigarette lighters.
Engine compartment
Under the hood, on the left side of the engine compartment, there can be 2 fuse boxes.
Fuse and relay box
To access the unit, you need to remove the protective cover.
Diagram
Designation
201 | 5A Alarm Siren |
202 | 20A Auxiliary heater control unit |
5A Electric Drive (W242): Terminal 87 relay of the parking lock control unit | |
203 | 15A Front right headlamp |
5A Electric Drive (W242): Transmission control unit | |
204 | 25A Electronic motion stabilization control unit |
205 | 15A Left horn |
Sound signal right | |
206 | 5A CDI control unit (engine 651) |
Transmission control unit (Electric Drive (W242)) | |
Brake Booster Vacuum Pump Relay (Electric Drive (W242)) | |
Relay el. circuit terminal 87M (Electric Drive (W242)) | |
207 | 5A Relay el. terminal circuits 87M (diesel) |
HV battery cooling shutoff valve (Electric Drive (W242)) | |
Parking lock control unit (Electric Drive (W242)) | |
208 | 7.5A Terminal 87 relay (motors: 133, 607) |
5A Electric Drive (W242): Fan motor | |
209 | 15A Front left headlight |
Electric Drive (W242): Reserved | |
210 | 5A Heated front window relay |
Starter pre-relay (as of 03/11/2014) | |
211 | 7.5A CNG control unit (242.848) |
15A Heating circuit circulation pump (Electric Drive (W242)) | |
212 | 15A Cable lug electr. terminal circuits 87M3 (motors 133, 270) |
Heating element of the ventilation pipeline (engine 651) | |
Heating element of the thermostat of the cooling system (engine 651) | |
EGR cooler bypass changeover valve (engine 651) | |
Lambda probe before catalytic converter (engine 607) | |
Boost pressure control servo (607 engine) | |
CDI control unit (engine 607) | |
Electric Drive (W242): Electric drive and charger coolant pump | |
213 | 15A Terminal 87 cable termination (motors 133, 270, 651) |
Camshaft Hall sensor (engine 607) | |
CDI control unit (engine 607) | |
Dosing valve (engine 607) | |
Lambda probe after catalytic converter (engine 607) | |
Electric Drive (W242): Coolant pump 1 for battery cooling | |
214 | 10A Terminal 87 cable termination (motors 133, 270, 651) |
15A Electric Drive (W242): Coolant pump 2 battery cooling | |
215 | 20A Cylinder 1 ignition coil (petrol engines) |
Cylinder 2 ignition coil (petrol engines) | |
Cylinder 3 ignition coil (petrol engines) | |
Cylinder 4 ignition coil (petrol engines) | |
Dosing valve (engine 651) | |
CDI control unit (engine 607) | |
Boost pressure control servo (607 engine) | |
Dosing valve (engine 607) | |
5A Electric Drive (W242): | |
Thermal management unit | |
Transmission Gateway Control Unit | |
High-voltage power distributor (since 03.11.2014) | |
216 | 5A ME control unit (petrol engines) |
Transmission control unit (engine 607) | |
217 | 25A Dual Clutch Transmission Fully Integrated Control Module (724 Transmission) |
218 | 5A Control unit for electronic stability control |
219 | 5A Electric Drive (W242): Parking lock control unit |
220 | 10A Circulation pump for gearbox oil cooling system (gearbox 724) |
221 | 40A Electric Drive (W242): Vacuum pump |
222 | 7.5A Electric Drive (W242): Electric air conditioner compressor |
223 | Reserve |
224 | 7.5A Electrical control module DISTRONIC |
COLLISION PREVENTION ASSIST control module | |
225 | 6A Electric Drive (W242): Transmission control unit |
226 | 5A CNG control unit (242.848) |
Charger control unit (Electric Drive (W242)) | |
Power electronics control unit (Electric Drive (W242)) | |
227 | 5A Electric Drive (W242): Power electronics control unit |
228 | 5A Electric Drive (W242): Electric vehicle sound generator |
229 | 5A Front left headlight |
230 | 5A Control unit for electronic stability control |
231 | 5A Front right headlamp |
232 | 15A Headlight control unit |
233 | Reserve |
234 | 5A Transmission control unit (engine 607) |
10A Electric Drive (W242): High voltage power distributor | |
235 | 7.5A Fan motor (607 motor) |
Radiator Shutter Actuator (607 Engine) | |
Charge air cooler circulation pump (engine 133) | |
236 | 40A SAM control unit |
237 | 40A Control unit for electronic stability control |
238 | 50A Heated windshield |
239 | 30A Wiper mode relay 1/2 |
240A | 25A Starter terminal 50 relay |
7.5A Electric Drive (W242): Transmission control unit | |
240B | 25A Terminal 15 relay (no support) |
241 | 7.5A Electric Drive (W242): High voltage electric heater system |
Relay | |
J | Horn relay |
K | Wiper speed relay 1/2 |
L | Wiper relay on/off |
M | Starter terminal 50 relay |
Electric Drive (W242): Terminal 87C Relay | |
N | Relay el. circuit terminals 87M |
O | Transmission oil coolant circulation pump relay |
Electric Drive (W242): Terminal 87 relay of the parking lock control unit | |
P | Reserve relay |
Q | Terminal 15 relay (unprotected) |
Electric Drive (W242): Brake booster vacuum pump power relay | |
R | Relay terminal 15 |
S | Relay terminal 87 |
T | Heated windshield relay |
Fuse box
The high power fuse box is located next to the fuse and relay box.
Diagram
Allocation
F1 | 300A Generator / 400A Electric Drive (W242): DC voltage converter control unit |
F2 | 200A Interior Fuse Box (Electric Drive (W242), and Gasoline Vehicles) |
250A Interior fuse block (Diesel engines) | |
F3 | 100A Electric power steering control unit |
F4 | 40A SAM control unit |
F5 | 80A Fan motor |
F6 | 70A Fuel heating control unit (engine 607) |
F7 | 125A DPF regeneration auxiliary heater control unit (engine 607) |
F8 | 100A Glow Plug Output Stage Module (Engines: 651, 607) |
Relay | |
F32k1 | Decoupling relay (F32k1) |
There is something to add – write in the comments.
May I know which fuse is related to Mass Air Flow sensor of Mercedes Class B 180 d 2026
Wiring diagram for c 300