Fuses and relays Volkswagen Polo 4 (9N / 9N3), 2001–2009

The fourth-generation VW Polo  was produced from 2001 to 2009 in both sedan and hatchback body styles. In 2005, the model underwent a facelift, which also introduced the crossover-styled CrossPolo. This publication details the locations of all electronic control units (ECUs) in the Volkswagen Polo Mk4 (chassis codes 9N, 9N3; A04 / PQ24 platform).

Detailed fuse and relay assignments, along with their location diagrams, are provided below.

General Component Layout

Arrangement of Electronic Control Units (ECUs):

No.	Control Unit / Component
1	Air conditioning control module – integrated into heater control panel
2	A/C heater blower motor control module (automatic climate control) – on blower unit
3	Audio system antenna amplifier – integrated into antenna base
4	Navigation system antenna amplifier – integrated into antenna base
5	Side impact sensor, driver side – under front seat
6	Side impact sensor, passenger side – under front seat
7	Side impact sensor, rear left (curtain airbag) – luggage compartment, behind left trim panel
8	Side impact sensor, rear right (curtain airbag) – luggage compartment, behind right trim panel
9	Anti-theft system control module – integrated into Central Control Unit 2 (BCM)
10	Anti-theft alarm horn/siren – behind rear left wheel arch trim
11	Volumetric interior motion sensor (anti-theft system) – integrated into front interior light
12	12V Battery
13	Central locking control module – integrated into Central Control Unit 2 (BCM)
14	Data Link Connector (DLC / OBD port)
15	Diagnostic gateway module – integrated into Central Control Unit 1 (BCM)
16	Door control module, front left (central locking / power mirror / power window)
17	Door control module, front right (central locking / power mirror / power window)
18	Door control module, rear left (central locking / power window)
19	Door control module, rear right (central locking / power window)
20	Radiator fan control module – with A/C (AXU engine)
21	Dashboard fuse/relay box 1
22	Dashboard fuse/relay box 2
23	Engine compartment fuse/relay box – above battery
24	Auxiliary fuse (5 A / 7.5 A / 10 A) – rear of audio/navigation head unit
25	Heater blower motor resistor (manual climate control) – on blower unit
26	Heater blower motor control module/resistor (automatic climate control) – integrated into blower unit

Passenger Compartment Fuse Box

The main fuse panel is located on the driver’s side end of the dashboard, behind a protective cover. Always verify current fuse assignments and ratings against the diagram on the inside of the fuse panel cover.

Sample photo.

Diagram
No.	Rating & Protected Circuits
1	10 A – Rear window wiper and washer pump
2	5 A – Instrument cluster illumination dimmer, license plate lamps
3	5 A – Rear fog lamps
4	5 A – Brake light switch (brake pedal sensor), cruise control, engine control module (ECU)
5	5 A – Engine control module (ECU), exhaust gas recirculation (EGR)
6	5 A – Headlight range control
7	5 A – Engine control module (ECU), power steering control module
8	5 A – Heated exterior mirrors
9	10 A – Engine control module (ECU)
10	5 A – Ignition switch S-contact (accessory power)
11	5 A – Electric exterior mirror adjustment / heating
12	5 A – Right front side marker lamp, right rear tail lamp
13	5 A – Left front side marker lamp, left rear tail lamp
14	10 A – Engine control module (ECU), intake manifold pre-heater
15	10 A – Automatic transmission control module
16	10 A – Windshield wiper and washer pump
17	5 A – Engine control module (ECU)
18	5 A – Air conditioning system, air recirculation flap, anti-theft system, auto-dimming interior rearview mirror, radiator fan control module, instrument cluster, navigation system
19	10 A – Heated windshield washer nozzles, reverse lamps
20	5 A – Instrument cluster
21	10 A – Right headlight (high beam)
22	10 A – Left headlight (high beam)
23	10 A – Anti-lock Braking System (ABS), Electronic Stability Program (ESP)
24	10 A – Central Control Unit 1 (BCM)
25	10 A – Engine control module (ECU)
26	10 A – Brake lamps
27	5 A – Anti-lock Braking System (ABS with ESP), instrument cluster
28	10 A – Interior lighting
29	5 A – Air conditioning, Data Link Connector (DLC / OBD), telephone prep
30	5 A – Central Control Unit 1 (BCM), automatic transmission shift lock, rain sensor
31	25 A – Front left power window motor
32	15 A – Heated front seats
33	15 A – Anti-theft alarm siren/horn
34	15 A – Auxiliary 12V power outlet
35	20 A – Power sunroof
36	25 A – A/C and heater blower motor
37	15 A / 20 A – Ignition coil(s), ignition system electronics
38	25 A – Rear left power window motor
39	25 A – Front right power window motor
40	10 A / 30 A – Engine control module (ECU)
41	15 A – Fuel pump / fuel transfer pump (gasoline / TDI)
42	20 A – Engine control module (ECU - AXU engine)
43	15 A – Right headlight (low beam), headlight range control
44	15 A – Front fog lamps
45	15 A – Engine control module (ECU - AUB engine)
46	20 A – Windshield wiper and washer pump
47	20 A – Heated rear window (from 02/04)
48	15 A – Turn signals, hazard warning flashers
49	15 A – Cigarette lighter
50	15 A – Central Control Unit 2 (BCM), anti-theft alarm system, central locking
51	15 A – Audio system, navigation system
52	20 A – Horn, windshield wiper and washer pump
53	25 A – Rear right power window motor
54	15 A – Left headlight (low beam), headlight range control

Fuse #49 (15 A) protects the cigarette lighter circuit.

Relay Box

The relay carrier is located behind the lower instrument panel trim on the driver’s side. The Polo features a unified relay carrier with standardized socket locations.

Diagram
No.	Description
1	Spare / Unassigned
2	Motronic engine management power supply relay
3	(100) Glow plug relay
4	(53) Fuel transfer pump relay (TDI)
5	(449) Door entry/exit warning lamp relay
6	(53) Headlight washer system relay
7	(126) Starter lockout relay
8	(53) Auxiliary heater relay 1 (low heat output)
9	(100) Auxiliary heater relay 2 (high heat output - diesel)
10	(53/429) Engine control module (ECU) relay (gasoline, except AXU)
11	(18) Load reduction relay (X-contact)
12	(404) Fuel system priming relay (gasoline, except AXU)
13	(167) Fuel pump relay (gasoline, except AXU)
14	Auxiliary heater fuse holder
15	(109) Engine control module (ECU) relay (diesel)

Additional fuses may also be mounted on this carrier, such as a 40 A fuse for the auxiliary heater.

Battery-Mounted Fuse Box

Located directly on the battery cover, this primary power distribution box protects major high-current circuits at the battery source. Its exact configuration depends on vehicle equipment. The carrier accommodates up to 6 high-current metal strip fuses and 10 blade fuses, connected to the positive battery terminal via a ring terminal bolt.

Diagram
No.	Rating & Protected Circuits
1	110 A – Alternator
2	110 A – Interior electrical distribution, ignition switch
3	50 A – Electro-hydraulic power steering pump
4	50 A – Engine control module (ECU - AXU engine), secondary air injection (SAI) pump
5	40 A – Radiator cooling fan
6	40 A – Anti-lock Braking System (ABS pump)
7	40 A – Anti-lock Braking System (ABS control unit)
8	30 A – Radiator cooling fan
9	Spare / Unassigned
10	5 A – Central Control Unit 1 (BCM)
11	5 A – Air conditioning, radiator fan control module
12	Spare / Unassigned
13	5 A – Automatic transmission control module
14	Spare / Unassigned
15	Spare / Unassigned
16	Spare / Unassigned