Main Relay

This procedure covers the replacement of the main relay (PGM-FI relay) in a 2018-2024 Honda Accord 1.5L Turbo, which controls power to the fuel injection system and engine control module.

Warnings

Tools required

Parts

• Main relay (PGM-FI relay) × 1 — Use OEM specification

Preparation

1. Park vehicle on level surface and engage parking brake
2. Turn ignition to OFF position and remove key
3. Wait at least 3 minutes after turning off ignition before beginning work
4. Open driver's door and locate the under-dash fuse/relay panel on the left side kick panel

Procedure

1. 1

   Disconnect battery negative terminal
   Open hood and locate battery in engine compartment. Using a 10mm socket, loosen the negative (-) battery terminal bolt and disconnect the cable. Secure cable away from battery post to prevent accidental contact.
   ⚠Always disconnect negative terminal first to prevent short circuits.
   Torque spec

   Battery Terminal Bolts6 Nm (4 lb-ft)
2. 2

   Remove under-dash panel
   Locate the under-dash fuse/relay panel cover on the driver's side lower kick panel. Pull the panel cover release tab at the bottom edge and swing the cover down and away to expose the fuse/relay box.
3. 3

   Locate main relay
   Using a flashlight, identify the main relay (PGM-FI relay) in the fuse/relay box. Refer to the diagram on the inside of the panel cover for exact location. The main relay is typically a larger relay module with multiple pins and is clearly labeled on the diagram.
4. 4

   Remove main relay
   Firmly grasp the main relay body and pull straight out with steady pressure. The relay is held in place by friction fit terminals. Rock gently side-to-side if needed, but do not bend or twist excessively. Inspect the relay socket terminals for any corrosion, burn marks, or damage.
   ⚠Do not force the relay or pry with tools as this can damage socket terminals.
5. 5

   Inspect relay socket
   Examine the relay socket in the fuse box for any signs of overheating, melted plastic, corroded terminals, or loose connections. If damage is present, the entire fuse/relay box may require replacement. Clean terminals with electrical contact cleaner if minor corrosion is present.
6. 6

   Install new main relay
   Align the new main relay with the socket, ensuring correct orientation by matching the pin configuration. Firmly press the relay straight into the socket until it seats completely and is flush with surrounding relays. Verify it is fully seated by gently attempting to pull it out.
   ⚠Ensure relay is oriented correctly before installation. Forcing relay in backwards will damage terminals.
7. 7

   Reinstall under-dash panel
   Position the under-dash panel cover back into place and press firmly until all clips engage and the panel is secure. Ensure the panel sits flush and does not rattle.
8. 8

   Reconnect battery
   Reconnect the negative battery cable to the negative terminal post. Tighten the battery terminal bolt to specification using a torque wrench. Ensure connection is secure but do not overtighten.
   Torque spec

   Battery Terminal Bolts6 Nm (4 lb-ft)

Reassembly

1. Ensure all panels are properly secured and clips are fully engaged
2. Verify under-dash panel does not interfere with pedal operation

Verification

• Turn ignition to ON position (do not start). Verify dashboard warning lights illuminate normally then extinguish
• Start engine and verify it cranks and starts normally without hesitation
• Allow engine to idle for 2-3 minutes and confirm no warning lights appear
• If applicable, reinitialize power windows by fully lowering and raising each window while holding the switch for 2 seconds at full up position
• Reset clock and radio presets as needed
• Verify no fuel system related trouble codes are stored using an OBD-II scanner

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