2005 Honda Odyssey Fuel Pump Relay Location: A Complete Guide for Owners

The bottom line: On a 2005 Honda Odyssey, the fuel pump relay is located inside the passenger compartment, specifically in the under-dash fuse/relay box on the driver's side. You will need to remove the left kick panel and door sill trim to access it. The relay is a rectangular blue component, and you can identify it by looking for the label "Fuel Pump" or "FP" on the fuse box diagram.

If your 2005 Odyssey cranks but refuses to start, or if it stalls unexpectedly while driving, a faulty fuel pump relay is one of the first things you should check. This guide will walk you through exactly where to find it, how to test it, and what to do if it needs replacement.

Where Exactly Is the Fuel Pump Relay on a 2005 Honda Odyssey?

The 2005 Honda Odyssey belongs to the third generation (2005-2010 model years). For this generation, the fuel pump relay is not under the hood. It is located inside the vehicle cabin. Here is the step-by-step process to find it:

1. Locate the driver's side kick panel. Sit in the driver's seat and look to your left, near your left knee. You will see a plastic trim panel covering the area below the dashboard.

2. Remove the left kick panel and door sill trim. You will need to carefully pull off the plastic trim. The door sill trim (the strip along the bottom edge of the door opening) may also need to be removed to give you enough room to work.

3. Find the interior fuse/relay box. Behind that trim panel, you will find the fuse box. This is a rectangular black box that contains multiple fuses and several relays.

4. Identify the fuel pump relay. The relay is a blue, rectangular component about the size of a large sugar cube. According to the fuse box diagrams for the 2005 model, the fuel pump relay is labeled as position R4 in the passenger compartment relay box. On the fuse box cover or in your owner's manual, look for the designation "Fuel Pump" or "FP".

5. Check the fuses as well. While you are there, also check fuse number 19 in the driver's side interior fuse box, which is a 15A fuse labeled "IG Fuel Pump". A blown fuse can mimic the symptoms of a bad relay.

Important note: Some owners have reported difficulty finding the relay because it is sometimes referred to as the PGM-FI Main Relay (Programmed Fuel Injection Main Relay), which actually contains two separate relays in one unit. On the 2005 model, this PGM-FI main relay assembly is located on the driver's side kick panel. One of the two internal relays (Main Relay 2) controls the fuel pump. If you are looking for "PGM-FI" on diagrams, this is the same component.

How the Fuel Pump Relay Works

Understanding how the relay functions will help you diagnose problems more effectively.

When you turn the ignition key to the ON position, the Engine Control Module (PCM) sends a signal to the relay coil, creating an electromagnetic field. This field pulls the contacts together, closing the circuit and allowing battery voltage to flow to the fuel pump.

The fuel pump then runs for about 2 seconds to prime the fuel system before you even crank the engine. If the engine does not start, the PCM disconnects the relay winding from ground, stopping the fuel pump for safety. Once the engine is running, the relay stays energized to keep the fuel pump operating.

For the 2005 Odyssey, there are actually two main relays working together. PGM-FI main relay 1 is energized whenever the ignition is on, supplying power to the PCM, injectors, and the second relay. PGM-FI main relay 2 is the actual fuel pump relay that supplies power directly to the fuel pump.

Common Symptoms of a Bad Fuel Pump Relay

A failing fuel pump relay can cause several noticeable problems. If you experience any of these symptoms, the relay should be one of the first components you check:

1. Engine cranks but won't start. This is the most common symptom. The starter motor turns the engine over normally, but the fuel pump does not receive power, so no fuel reaches the injectors. Your engine will crank endlessly without firing up.

2. Intermittent starting problems. Your Odyssey may start fine one day and refuse to start the next. This inconsistent behavior is often caused by a relay with corroded contacts or a broken coil wire that only fails intermittently.

3. Engine stalls while driving. If the relay fails while you are driving, the engine can stall without any warning. This is a serious safety concern, especially if you are on the highway or in heavy traffic.

4. No fuel pump priming sound. When you turn the key to the ON position (without cranking), you should hear a brief whirring sound from the fuel pump near the rear of the vehicle. If you hear nothing, the relay or the pump itself may be faulty. The fuel pump should run for about 1-2 seconds to pressurize the system.

5. Check Engine Light. A faulty relay can trigger a check engine light with diagnostic trouble codes related to the fuel pump circuit.

How to Test the Fuel Pump Relay

Before you buy a new relay, take a few minutes to test the existing one. These tests are simple and can save you money.

Test 1: Listen for the fuel pump. Turn the ignition to the ON position but do not start the engine. Have a helper listen near the rear of the vehicle (near the fuel tank) for a brief hum or whirring sound. If you hear it for 1-2 seconds, the relay is likely working. If you hear nothing, further testing is needed.

Test 2: Swap the relay. Find a relay in the fuse box that is the same size, shape, and part number. Good candidates include the horn relay, A/C relay, or the rear defroster relay. Swap that known-good relay into the fuel pump relay socket. If the fuel pump now works (you hear the priming sound), the original relay was faulty. If it still does not work, the issue is elsewhere.

Test 3: Use a multimeter. Remove the relay from its socket. Check for continuity between the coil terminals (usually the two smaller terminals). Then, apply 12V power to the coil terminals and check that the switch contacts (the two larger terminals) close properly. If the relay fails either test, it needs replacement.

Test 4: Check for power at the socket. With the ignition in the ON position, use a test light or multimeter to check the relay socket. You should have battery voltage (12V) on pins 1 and 4 of the socket. Pin 1 gets power from the 15A fuse number 19 (IG Fuel Pump). Pin 4 gets power from PGM-FI Main Relay 1. If these pins have no power, check the fuses first.

Important safety warning: If you have previously jumped the fuel pump relay with a paperclip or wire and your vehicle now refuses to start with the relay installed, you may have damaged the PCM (Engine Control Module). The PCM controls the ground circuit for the relay. Jumping the wrong pins can send power to the PCM's transistor and fry it. If you suspect this, you will likely need professional diagnostic help.

How to Replace the Fuel Pump Relay

Replacing the fuel pump relay on a 2005 Honda Odyssey is a straightforward DIY job. Here is what you need to know:

What you need:

  • A new fuel pump relay. For the 2005 Odyssey, the genuine Honda part number is 39794-SDA-004 (Denso brand) or 39794-SDA-A03 for later style relays. This part is also known as a Relay Assembly, Fuel Pump.
  • A small flathead screwdriver or trim removal tool to remove the kick panel.

Steps:

  1. Disconnect the negative battery terminal (optional but recommended).
  2. Remove the driver's side kick panel and door sill trim as described earlier.
  3. Locate the blue relay in the fuse box.
  4. Firmly grasp the relay and pull it straight out of its socket. It may require a bit of force.
  5. Insert the new relay into the same socket. Push down firmly until it clicks into place.
  6. Reinstall the trim panels and door sill trim.
  7. Reconnect the battery if you disconnected it.
  8. Test by turning the ignition to ON and listening for the fuel pump priming sound.

Cost estimate: If you do the work yourself, the relay part costs around $33, and the total job at a shop typically runs $128 to $200 depending on your location.

What If the Relay Is Not the Problem?

If you have tested the relay and replaced it, but your Odyssey still has starting or stalling issues, consider these other possible causes:

  • Blown fuel pump fuse. Check fuse number 19 (15A) in the driver's side interior fuse box. Also check fuse number 8 (15A) labeled "FI ECU" in the engine compartment primary fuse box.
  • Faulty fuel pump. The pump itself may have failed. Listen for the priming sound near the rear of the vehicle.
  • Faulty PGM-FI Main Relay 1. This relay supplies power to the fuel pump relay. If it fails, the fuel pump relay will not get power.
  • Wiring issues. Corroded or damaged wiring between the relay and the fuel pump can cause problems.
  • Failed PCM. As mentioned earlier, jumping the relay incorrectly can damage the PCM. This requires professional diagnosis.

Upgrade Your Fuel System with KEMSO

If you discover that your fuel pump itself needs replacement, or if you simply want to ensure your 2005 Honda Odyssey has the best possible fuel delivery, consider a KEMSO fuel pump. KEMSO is a trusted brand known for manufacturing high-performance, OEM replacement fuel pumps that are designed to meet or exceed factory specifications.

KEMSO fuel pumps are built for durability and reliability. Each pump delivers superior flow rates compared to stock units, ensuring your engine gets the fuel it needs under all driving conditions. Whether you are dealing with a failed factory pump or you want to upgrade for better long-term performance, KEMSO offers a direct fit solution that installs easily without modification. Best of all, every KEMSO fuel pump comes with a lifetime warranty, giving you complete peace of mind on the road.

Visit KEMSO Racing today to find the perfect fuel pump for your Honda Odyssey or any other vehicle in your garage. Their product lineup covers a wide range of makes and models, and their customer support team is ready to help you choose the right part. For more information and to browse their full selection, go to https://www.kemsoracing.com/.


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