Fuel Pump Relay

This procedure covers locating and replacing the fuel pump relay in the under-hood fuse/relay box on 2018-2024 Honda Accord 1.5L Turbo models.

Warnings

Tools required

Parts

• Fuel pump relay × 1 — Honda 39794-SDA-A03 or equivalent MITSUBA relay

Preparation

1. Park vehicle on level ground and apply parking brake
2. Turn ignition to OFF position and remove key from vehicle
3. Allow engine to cool if recently operated (under-hood components may be hot)
4. Gather replacement relay and verify correct part number against vehicle specifications
5. Locate under-hood fuse/relay box on driver's side of engine compartment near battery

Procedure

1. 1

   Access the under-hood fuse/relay box
   Open the hood and locate the under-hood fuse/relay box on the driver's side near the battery. Press the tabs on both sides of the cover and lift upward to remove the fuse box cover. The relay diagram is printed on the underside of the cover.
2. 2

   Identify the fuel pump relay location
   Reference the relay diagram on the fuse box cover to locate the fuel pump relay. On 2018-2024 Accord 1.5T models, the fuel pump relay (PGM-FI Main Relay 2) is typically located in position R27 or R28 depending on model year. It is a black rectangular relay with four or five pins. Verify identification using the cover diagram before proceeding.
3. 3

   Test fuel pump relay operation (optional diagnostic step)
   If diagnosing a no-start condition, turn ignition to ON position (do not start). Listen for fuel pump priming sound (2-3 second hum from rear of vehicle). Turn ignition OFF. With ignition OFF, you may swap the fuel pump relay with an identical relay from another position (such as headlight or horn relay) to test if symptoms change. Return ignition to OFF before removing any relay.
4. 4

   Remove the fuel pump relay
   With ignition OFF and key removed, grasp the fuel pump relay firmly and pull straight upward with steady pressure. If relay is difficult to remove, use needle-nose pliers or a relay puller tool, gripping the relay body (not the terminals). Rock gently side-to-side while pulling upward to release from socket. Do not use excessive force that could damage socket terminals.
5. 5

   Inspect relay socket and terminals
   Examine the relay socket for corrosion, burnt terminals, or damaged contacts. Check for presence of moisture or debris inside socket. If socket shows heat damage (melted plastic, discolored terminals), the socket assembly may require replacement by a qualified technician. Minor corrosion can be cleaned with electrical contact cleaner and allowed to dry completely.
6. 6

   Test old relay (optional verification step)
   Using a digital multimeter, test the old relay for proper operation. Check for continuity between relay terminals per Honda specifications. A functioning relay should show open circuit between load terminals when not energized, and closed circuit when coil terminals receive 12V. If unfamiliar with relay testing, proceed to installation of new relay.
7. 7

   Install new fuel pump relay
   Verify new relay matches the original relay configuration (same number of pins and physical dimensions). Align relay pins with socket terminals, ensuring correct orientation. Press relay firmly into socket until fully seated with an audible click. Relay should sit flush with surrounding relays and not protrude above socket. Do not force if relay does not seat easily; verify pin alignment and correct relay type.
8. 8

   Reinstall fuse box cover and test operation
   Align fuse box cover with housing and press down until tabs click into place. Ensure cover is fully secured. Turn ignition to ON position (do not start engine) and listen for fuel pump priming sound from rear of vehicle (2-3 second hum). If pump primes, attempt to start engine. Engine should start normally if relay was the only issue.

Reassembly

1. Ensure fuse box cover is properly secured with all tabs engaged
2. Verify no tools or parts are left in engine compartment
3. Close hood completely

Verification

• Turn ignition to ON position and confirm fuel pump primes for 2-3 seconds (listen for hum from rear of vehicle)
• Start engine and verify normal operation with no hesitation or stalling
• Check for proper idle and throttle response
• Turn engine OFF and restart to confirm fuel pump relay operates consistently
• Verify no warning lights on instrument cluster related to fuel system
• Test drive vehicle to confirm normal acceleration and no fuel delivery issues under load

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