Mercedes-Benz B-Class Fuse Box Locations and Diagrams (2011-2018)

The second-generation Mercedes-Benz B-Class (W246, W242), produced from 2011 to 2018, is a premium compact MPV that blends practicality with the brand’s signature refinement. With its elevated seating position, spacious interior, and a wide range of efficient engines, the B-Class caters to drivers seeking both comfort and versatility. Known for its safety features, advanced infotainment, and urban-friendly design, the W246 generation stands out as a well-rounded family vehicle.

In this article, you will find fuse box diagrams for the Mercedes-Benz B-Class, covering models B160, B180, B200, B220, and B250 for the years 2011, 2012, 2013, 2014, 2015, 2016, 2017, and 2018. These diagrams offer essential insights into the fuse layout, helping owners and technicians locate, identify, and understand the function of each fuse and relay in the vehicle’s electrical system.

What’s Included:

  • Fuse Box Diagrams – Visual references to clearly identify fuses, relays, and circuit breakers by position and function.
  • Fuse Panel Locations – Easy-to-follow instructions for locating fuse panels inside the cabin and engine compartment.
  • Fuse Assignments – Detailed listings of what each fuse and relay controls, to simplify troubleshooting and maintenance.

Whether you’re diagnosing a malfunctioning accessory, replacing a blown fuse, or working on electrical repairs, this guide is an indispensable tool for keeping your Mercedes-Benz B-Class (W246, W242) running smoothly.

Maintain peak performance and reliability with this comprehensive fuse panel, fuse box, and relay layout reference!

  • The cigar lighter (power outlet) fuses are located in the Passenger Compartment Fuse Box:
    • Fuse №70: Rear Center Console Socket
    • Fuse №71: Luggage Compartment Socket
    • Fuse №72: Front Cigarette Lighter / Interior Power Outlet

Passenger Compartment Fuse Box

Fuse box location

The fuse box is located under the floor near the passenger seat.Fold out perforated floor covering (1) in the direction of the arrow.
To release cover (3), press retaining clamp (2).
Fold-out cover (3) in the direction of the arrow to the catch.
Remove cover (3) forwards.
Fuse allocation chart (4) is located on the lower right-hand side of the cover (3).

The location of the fuses in the passenger compartment: Mercedes-Benz B-Class (2012-2018)

Fuse box diagram

Interior fuse box diagram: Mercedes-Benz B-Class (2012-2018)

Assignment of the fuses and relay in the passenger compartment

№Fused functionAmp
21Valid for diesel engine: PTC heater booster150
22Additional battery relay for ECO start/stop function200
23Left front door control unit30
24Right front door control unit30
25SAM control unit30
26ECO start/stop additional battery connector sleeve10
27Engine compartment fuse and relay module30
28Vehicle interior sound generator control unit
Electric Drive (W242): Thermal management control unit		5
29up to 02.11.2014: Trailer socket
as of 03.11.2014: Trailer recognition control unit		15
30Trailer recognition control unit5
314MATIC: All-wheel drive control unit5
32Steering column tube module control unit5
33Audio/COMAND control panel5
34ACC control and operating unit7,5
35Rear window heater40
36Driver seat control unit
Driver seat lumbar support adjustment control unit		7,5
37Audio/COMAND display7,5
38Supplemental Restraint System control unit7,5
39Overhead control panel control unit10
40Valid for engine 651 (Emissions standard EU6): Powertrain control unit15
40Electric Drive (W242): Powertrain control unit5
41Panoramic sliding sunroof control module30
42Radio (Audio 5 USB, Audio 20 CD, Audio 20 CD with CD changer)
COMAND controller unit		5
42Radio (Radio 20, Audio 20 USB)25
43Parking system control unit5
44Left front reversible emergency tensioning retractor40
45Right front reversible emergency tensioning retractor40
46Front passenger seat control unit
Front passenger seat lumbar support adjustment control unit		7,5
47Navigation module7,5
47Adaptive damping system control unit25
48Spare–
49Control unit for Drive Kit for iPhone®7,5
49COMAND fan motor5
50Spare–
51Spare–
52Electric Drive (W242): Park pawl actuator motor30
53Spare–
54Spare–
55Telematics services communications module
KEYLESS-GO control unit		5
56Steering column tube module control unit10
57Lane Keeping Assist: Special-purpose vehicle multifunction control unit30
57Special vehicle: Special-purpose vehicle multifunction control unit7.5
57Electric Drive (W242): Park pawl actuator motor circuit 87 relay (F34kG)5
58Emergency vehicle fuse box30
59Front passenger seat control uni30
60Driver seat control unit30
61Sound system amplifier control unit40
62Valid for transmission 711: Electric steering lock control unit20
63Fuel system control unit25
63Electric Drive (W242): Gateway powertrain control unit5
64Electronic Toll Collection control unit
Dedicated Short-Range Communications control unit		1
65Glove compartment lamp5
66Emergency vehicle fuse box15
66Special-purpose vehicle interface5
67Spare–
68Spare–
69Spare–
70Rear center console socket25
71Luggage compartment socket25
72Front cigarette lighter with ashtray illumination
Vehicle interior power outlet		25
73Electric parking brake control unit30
74Electric parking brake control unit30
75Trailer recognition control unit20
75Electric Drive (W242): Battery management system control unit (N82/2)5
76Trailer recognition control unit (N28/1)25
76Electric Drive (W242): Park pawl control unit5
77Trailer recognition control unit25
78Emergency vehicle fuse box40
79SAM control unit40
80SAM control unit40
81Blower regulator40
82Overhead control panel control unit10
83Electronic ignition lock control unit7,5
84Upper control panel control unit5
85ATA [EDW]/tow-away protection/interior protection control unit5
86FM, AM and CL [ZV] antenna amplifier
as of 01.06.2016: Cellular telephone system antenna amplifier / compensator		5
87Diagnostic connector10
88Instrument cluster10
89Exterior lights switch5
90Left rear bumper intelligent radar sensor
Intelligent radar sensor for right rear bumper		5
91Pedal operation monitor switch
Footwell illumination switch
Electric Drive (W242): Battery management system control unit		5
92Fuel system control unit
Electric Drive (W242): Gateway powertrain control unit		5
93Electric parking brake control unit5
94Supplemental Restraint System control unit7,5
95Front passenger seat occupied recognition and ACSR
Weight sensing system (WSS) control unit		7,5
96Tailgate wiper motor15
97Mobile phone electrical connector5
98SAM control unit5
99Tire pressure monitor control unit5
100Valid for engine 133: DIRECT SELECT INTERFACE5
1014MATIC: All-wheel drive control unit10
102Stationary heater radio remote control receiver

Electric Drive (W242): Powertrain control unit

Valid for AMG vehicles as of 01.09.2015: Transmission mode control unit

as of 01.06.2016: Antenna changeover switch for telephone and stationary heater		5
103Emergency call system control unit
Telematics services communications module
HERMES control unit		5
104Media interface control unit
Multimedia connection unit		5
105Digital Audio Broadcasting control unit
Satellite digital audio radio (SDAR) control unit		5
105Tuner unit7,5
106Multifunction camera5
107Digital TV tuner5
108up to 31.05.2016: Reversing camera5
108as of 01.06.2016: Reversing camera7,5
109Charging socket electrical connector20
110Radio
COMAND controller unit
Engine sound control unit		30
Relay
ACircuit 15 relay
BRear window wiper relay
CCircuit 15R2 relay
DHeated rear window relay
ECircuit 15R1 relay
FCircuit 30g relay
GElectric Drive (W242): Park pawl actuator motor circuit 87 relay

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Front Electrical Pre-fuse Box

Front Electrical Pre-fuse Box

№Fused functionAmp
1Alternator300
1Electric Drive (W242):  DC/DC converter control unit 400
2Vehicle interior fuse box200(petrol)
250(diesel)
3Electrical power steering control unit100
4SAM control unit40
5Fan motor80
6Valid for engine 607: Fuel preheating control unit70
7Valid for engine 607 (Emissions standard EU5): DPF regeneration heater booster control unit125
8Valid for engine 607, 651: Glow output stage100
Relay
F32klDecoupling relay

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Engine Compartment Fuse Box

Fuse box location

The location of the fuses in the engine compartment: Mercedes-Benz B-Class (2012-2018)

Fuse box diagram

Under-hood fuse box diagram: Mercedes-Benz B-Class (2012-2018)

Assignment of the fuses and relay in the engine compartment

№Fused functionAmp
201Alarm siren5
202Stationary heater control unit20
202Electric Drive (W242): Park pawl control unit circuit 87 relay5
203LED headlamp: Right front lamp unit15
203Electric Drive (W242): Powertrain control unit5
204Electronic Stability Program control unit25
205Left fanfare horn
Right fanfare horn		15
206Valid for engine 651: CDI control unit
Valid for engine 607: Powertrain control unit
Electric Drive (W242): Brake booster vacuum pump relay Circuit relay 87M		5
207Valid for diesel engine: Circuit relay 87M
Electric Drive (W242): High-voltage battery cooling shutoff valve Park pawl control unit		5
208Valid for engine 133, 607: Circuit 87 relay7.5
208Electric Drive (W242): Fan motor5
209LED headlamp: Left front lamp unit15
209Electric Drive (W242): Spare–
210Heated windshield relay5
210as of 03.11.2014 except (Canada version): Starter front-end relay5
211Natural Gas Drive (W242): CNG control unit7.5
211Electric Drive (W242): Heater circuit circulation pump15
212Valid for engine 133, 270: Connector sleeve, circuit 87M3

Valid for engine 651:
Vent line heater element
Coolant thermostat heating element
Exhaust gas recirculation cooler bypass switchover valve

Valid for engine 607 (Emissions standard EU5):
Oxygen sensor upstream of catalytic converter
Boost pressure positioner

Valid for engine 607 (Emissions standard EU6): Oxygen sensor upstream of catalytic converter

Valid for engine 607: CDI control unit

Electric Drive (W242): Electric drive and charger coolant pump		15
213Valid for engine 133, 270, 651: Connector sleeve, circuit 87 M2e

Valid for engine 607 (Emissions standard EU5):
Camshaft Hall sensor
CDI control unit
Quantity control valve

Valid for engine 607 (Emissions standard EU6):
Oxygen sensor downstream of catalytic converter
CDI control unit

Electric Drive (W242): Battery cooling system coolant pump 1		15
214Valid for engine 133, 270, 651: Connector sleeve, circuit 87 M4e10
214Electric Drive (W242): Battery cooling system coolant pump 215
215Valid for gasoline engine:
Cylinder 1 ignition coil
Cylinder 2 ignition coil
Cylinder 3 ignition coil
Cylinder 4 ignition coil

Valid for engine 651: Quantity control valve

Valid for engine 607:
CDI control unit
Boost pressure positioner
Quantity control valve		20
215Electric Drive (W242):
Thermal management control unit
Gateway powertrain control unit

Electric Drive (W242) as of 03.11.2014: High-voltage power distributor		5
216Valid for gasoline engine: ME-SFI control unit

Valid for engine 607: Powertrain control unit		5
217Valid with transmission 724: Dual clutch transmission fully integrated transmission control unit25
218Electronic Stability Program control unit5
219Electric Drive (W242): Park pawl control unit5
220Transmission cooling coolant circulation pump10
221Electric Drive (W242): Vacuum pump40
222Electric Drive (W242): Electrical refrigerant compressor7.5
223Spare–
224DISTRONIC electric controller unit
COLLISION PREVENTION ASSIST controller unit		7.5
225Electric Drive (W242): Powertrain control unit5
226Natural Gas Drive (W242): CNG control unit
Electric Drive (W242): Charger control unit Power electronics control unit		5
227Electric Drive (W242): Power electronics control unit5
228Electric Drive (W242): Electric vehicle sound generator5
229Left front lamp unit5
230Electronic Stability Program control unit5
231Right front lamp unit5
232Headlamp control unit15
233Spare–
234Valid for engine 607: Powertrain control unit5
234Electric Drive (W242): High-voltage power distributor10
235Valid for engine 607: Fan motor, Radiator shutters actuator7.5
235Valid for engine 133: Charge air cooler circulation pump, Charge air cooler circulation pump7.5
236SAM control unit40
237Electronic Stability Program control unit40
238Heated windshield50
239Wiper speed 1/2 relay30
240AStarter circuit 50 relay25
240AElectric Drive (W242): Powertrain control unit7.5
240BCircuit 15 relay (not latched)25
241Electric Drive (W242): High-voltage PTC heater7.5
Relay
JFanfare horn relay
KWiper speed 1/2 relay
LWindshield wiper ON/OFF relay
MStarter circuit 50 relay
Electric Drive (W242): Circuit 87C relay
NCircuit relay87M
0ECO start/stop: Transmission cooling coolant circulation pump relay
Electric Drive (W242): Park pawl control unit circuit 87 relay
PBackup relay (F58kP)
QCircuit 15 relay (not latched)
Electric Drive (W242): Brake booster vacuum pump supply relay (F58kQ)
RCircuit 15 relay
SCircuit 87 relay
THeated windshield relay

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