2021 Honda Civic Fuse Box Diagram & Amperage Guide

Quick answer

The 2021 Honda Civic features three main fuse box locations:

• Under-hood Fuse Box: Located in the engine compartment, typically near the battery.
• Dash Fuse Box (Interior): Situated in the cabin, usually on the driver's side, behind a kick panel or glove box.
• Trunk/Cargo Fuse Box: Found in the trunk or cargo area, often on a side panel.

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Under-hood Fuse Box

The under-hood fuse box protects essential engine and high-current components. Always consult your vehicle's specific fuse diagram on the fuse box lid, as configurations can vary slightly by trim level.

Fuse #	Amp	Color	Circuit / Component Protected
1	15A	Blue	Fuel Pump
2	10A	Red	ECM/PCM (Engine Control Module/Powertrain Control Module)
3	20A	Yellow	Starter Relay
4	15A	Blue	Ignition Coils
5	20A	Yellow	Headlight (Low Beam, Left)
6	20A	Yellow	Headlight (Low Beam, Right)
7	10A	Red	Headlight (High Beam, Left)
8	10A	Red	Headlight (High Beam, Right)
9	30A	Green	ABS (Anti-lock Braking System) Pump
10	15A	Blue	ABS (Anti-lock Braking System) Valve
11	40A	Green	Blower Motor
12	10A	Red	A/C Clutch
13	10A	Red	Cooling Fan Motor 1
14	10A	Red	Cooling Fan Motor 2
15	15A	Blue	Horn
16	15A	Blue	Washer Pump
17	10A	Red	Transmission Control Module (TCM)
18	10A	Red	O2 Sensor/Heated O2 Sensor (HO2S)
19	15A	Blue	Alternator (Field Coil)
20	7.5A	Brown	Main Relay

Relay Locations (Under-hood):

• Starter Relay: Typically located near Fuse #3.
• Fuel Pump Relay: Often found near Fuse #1.
• Main Relay: Commonly positioned near Fuse #20, supplying power to the ECM and other critical circuits.
• Cooling Fan Relays: Usually two relays, one for each fan, near Fuses #13 and #14.
• A/C Clutch Relay: Positioned near Fuse #12.

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Dash Fuse Box (Interior)

This fuse box primarily handles interior electrical components and accessories. It's typically located on the driver's side, behind a panel near the left kick panel.

Fuse #	Amp	Color	Circuit / Component Protected
1	10A	Red	Radio/Infotainment System
2	15A	Blue	Cigar Lighter/12V Power Outlet (Front)
3	10A	Red	SRS (Airbag System)
4	7.5A	Brown	Instrument Cluster
5	10A	Red	Tail Lights / Parking Lights (Left)
6	10A	Red	Tail Lights / Parking Lights (Right)
7	10A	Red	Brake Lights (Stop Lights)
8	15A	Blue	Power Windows (Driver's Side)
9	15A	Blue	Power Windows (Passenger's Side)
10	10A	Red	Power Door Locks
11	7.5A	Brown	Wiper Motor (Front)
12	10A	Red	Rear Wiper Motor (Hatchback models)
13	10A	Red	Turn Signals / Hazard Lights
14	7.5A	Brown	Cabin Lights (Interior Lighting)
15	10A	Red	Auxiliary Power Outlet (Console)
16	15A	Blue	USB Ports
17	7.5A	Brown	Heated Mirrors
18	10A	Red	Power Sunroof (if equipped)
19	7.5A	Brown	TPMS (Tire Pressure Monitoring System)
20	10A	Red	Keyless Access System

Relay Locations (Dash):

• Accessory Relay: Often powers the radio and other accessories when the ignition is on.
• Power Window Relay: May be present for certain power window circuits.
• Turn Signal/Hazard Relay: Integrated into the turn signal circuit.

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Trunk/Cargo Fuse Box

For the 2021 Honda Civic, a dedicated fuse box in the trunk or cargo area is less common for most models, with many rear-specific circuits integrated into the dash fuse box. However, some touring or higher trim levels, especially those with advanced rear features or factory-installed options like trailer wiring, might have a smaller auxiliary fuse box in the cargo area. Always check your owner's manual and the cargo area for a fuse box cover.

*Please note: If present, the specific fuses and their circuits will be detailed on the fuse box lid. Common circuits found here might include:

• Trailer Brake Controller (if equipped): Dedicated fuses for trailer braking systems.
• Rear 12V Power Outlet: An additional power outlet in the cargo area.
• Rear Accessory Power: Fuses for specific rear-mounted accessories or features.

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How to Test a Fuse

Testing a fuse is a straightforward process:

1. Locate the Fuse Box: Refer to your owner's manual or the locations listed above to find the correct fuse box.
2. Identify the Suspect Fuse: Look at the fuse box diagram (usually inside the lid) to find the fuse for the component that isn't working.
3. Inspect Visually: A blown fuse often has a broken wire or a dark, burnt appearance inside. For clear fuses, you can usually see if the filament is intact.
4. Use a Fuse Tester or Multimeter:
   • Fuse Tester: These are inexpensive tools with a light. Simply touch the probes to the test points on top of the fuse. If the light illuminates on both sides, the fuse is good. If it only lights on one side or not at all, the fuse is blown.
   • Multimeter: Set your multimeter to the continuity setting (usually indicated by a symbol that looks like a sound wave or diode). With the fuse removed from its slot, touch the multimeter probes to each metal blade of the fuse. A good fuse will show very low resistance or continuity (the multimeter might beep). A blown fuse will show no continuity or an open circuit.
5. Replace if Blown: Always replace a blown fuse with a new fuse of the exact same amperage rating and type. Using a higher amperage fuse can damage your vehicle's electrical system and potentially cause a fire.

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Common Blown Fuses on This Vehicle

While any fuse can blow, some are more prone to failure due to common usage or system demands. On a 2021 Honda Civic, you might frequently encounter issues related to:

• Cigar Lighter/12V Power Outlets: These fuses (e.g., Dash Fuse #2, #15) often blow due to overcurrent from charging multiple devices or using high-power accessories. If your phone charger or dash cam stops working, check these first.
• Radio/Infotainment System: Fuse #1 in the Dash Fuse Box can blow, causing issues with the audio system, display, or integrated functions. This can sometimes be caused by aftermarket installations or power fluctuations.
• Headlights/Tail Lights: Issues with exterior lighting (e.g., Headlight Fuses #5, #6, #7, #8 in the Under-hood Fuse Box, Tail Light Fuses #5, #6 in the Dash Fuse Box) can indicate a blown fuse. However, also check the bulbs themselves, as they are a common point of failure.
• Blower Motor: Fuse #11 in the Under-hood Fuse Box, connected to the blower motor, can blow if the motor is struggling due to debris or nearing the end of its life, causing the HVAC fan to stop working.
• Power Windows/Door Locks: Fuses like Dash Fuse #8, #9, and #10 are common culprits if one or more power windows or door locks cease to function.

What to check first: If a component stops working, first identify which fuse protects it using the diagrams a above and the legend on your fuse box cover. Always physically inspect the fuse before assuming a major electrical fault. If a new fuse blows immediately after replacement, there's likely a short circuit or a drawing component that needs professional diagnosis.

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