2004 WRX Fuel Pump Relay Location: The Complete Guide to Finding and Testing It
If you own a 2004 Subaru WRX and the engine cranks but won't start, the fuel pump relay is one of the first things you should check. The fuel pump relay on a 2004 WRX is located behind the passenger side kick panel, under the glove box. It is a green relay with a green connector plug, and it sits in a relay block on the back side of the glove box assembly . The factory part number for this relay is 82501AA130, which also supersedes the earlier part number 82501AA000 .
This guide will walk you through exactly where to find the relay, how to test it, what symptoms point to a bad relay, and what to do if the relay is not the problem.
Understanding the Fuel Pump Relay in Your 2004 WRX
The fuel pump relay is an electromechanical switch that controls power delivery to the fuel pump. When you turn the ignition key to the "ON" position, the Engine Control Module (ECM) sends a signal to energize the relay coil, which closes the relay contacts and sends battery voltage to the fuel pump . This is what makes the fuel pump prime for a couple of seconds before you start the engine.
The relay itself is located in the under-dash relay block, but the exact spot depends a bit on whether you have a WRX or an STI model. For the 2004 WRX and STI, the service manual clearly states it is on the back side of the glove box, behind the passenger side kick panel . This is different from many other cars where the fuel pump relay is in the main engine bay fuse box.
How to Access the Fuel Pump Relay
Getting to the relay is a straightforward job that takes about 10 minutes. Here is the step-by-step process:
1. Open the passenger side front door. You need access to the area below the glove box on the passenger side.
2. Remove the passenger side front side sill cover. This is the plastic trim piece that runs along the bottom of the door opening. It usually just pulls up and off with some firm pressure .
3. Locate the relay block. Look up behind the glove box area, toward the back side of the dashboard. You will see a small relay block mounted to the body. It holds several relays.
4. Find the green relay. The fuel pump relay is green and has a green connector plug attached to it . It is usually the only green relay in that block, which makes it easy to identify.
5. Remove the relay. There is a small bolt that holds the relay bracket to the body. Remove that bolt, then unplug the connector from the relay to pull it out .
Some owners also report finding the fuel pump relay behind the coin tray next to the steering wheel on the driver's side, but the factory service manual and most forum discussions confirm the passenger side kick panel as the correct location for the 2004 model year .
Symptoms of a Bad Fuel Pump Relay
A failed fuel pump relay will prevent the fuel pump from running, which means the engine gets no fuel. Here are the most common symptoms:
1. Engine cranks but will not start. This is the number one symptom. You turn the key, the starter motor spins the engine, but it never fires up. You may not hear the fuel pump prime when you turn the key to "ON."
2. No fuel pump priming sound. When you turn the ignition to the "ON" position (not cranking), you should normally hear a faint whirring sound from the rear of the car for about 2 seconds. If you hear nothing, the relay may not be sending power to the pump.
3. Intermittent starting issues. Sometimes the car starts fine, other times it cranks but won't start. This can happen when the relay contacts are worn and only make connection sporadically.
4. Car stalls while driving. If the relay fails while you are driving, the engine will suddenly lose power and stall. You will lose all power assist for steering and brakes, so this is a safety concern.
How to Test the Fuel Pump Relay
Before you go buy a new relay, you can test the old one to confirm it is bad. The factory service manual provides specific resistance values to check .
1. Visual inspection. First, look at the relay for any signs of physical damage, cracks, or corrosion on the terminals .
2. Check the coil resistance. Using a digital multimeter set to ohms, measure the resistance between terminals 3 and 4 on the relay. The factory spec is 93.8 to 136.4 ohms when measured at 68°F (20°C) . If you get infinite resistance (open circuit) or a reading way outside that range, the relay coil is bad.
3. Check the switch contacts. Measure the resistance between terminals 1 and 2. With no power applied to the coil, you should read 1 megohm or more (essentially an open circuit) . This is the normal "resting" state where the contacts are open.
4. Apply power to the coil. Connect battery positive to terminal 3 and battery ground to terminal 4. With the coil energized, the relay should click, and the resistance between terminals 1 and 2 should drop to less than 1 ohm . If the relay clicks but the resistance stays high, the internal contacts are burned.
What to Do If the Relay Tests Good
If your fuel pump relay passes all the tests, the problem is likely elsewhere in the fuel system. Here are the next things to check:
1. Check the fuel pump fuse. Look in the fuse and relay box behind the left side of the dash. There is a 10-amp fuse that protects the fuel pump circuit . A blown fuse will also prevent the pump from running.
2. Test for power at the fuel pump. The fuel pump is located inside the fuel tank. On the sedan, it is accessed through an access panel in the trunk on the passenger side . On the wagon, it is under the rear seat . Use a multimeter to check for 12 volts at the pump connector when the key is turned to "ON."
3. Check the fuel pump itself. If you have power to the pump but it does not run, the pump motor has likely failed. Many owners report that the original pump makes a "sickly whine" before it completely dies . Replacing the pump with an aftermarket unit like a Walbro 255 is a common fix .
4. Inspect the fuel pump controller. The 2004 WRX uses a fuel pump control module that regulates pump speed based on engine demand. This module can also fail and cause no-start conditions .
5. Check the main relay. There is also a main relay in the same relay block behind the glove box. This relay provides power to the ECM and other critical systems. If the main relay fails, the ECM never wakes up, and the fuel pump relay never gets the signal to close .
Replacement Part Information
The OEM fuel pump relay for the 2004 Subaru WRX and STI is part number 82501AA130, which replaced the earlier part number 82501AA000 . This relay is also used in other Subaru models including the Baja, Forester, Legacy, and Outback from the same era .
If you need to replace the relay, an OEM unit typically costs around $35 MSRP . Aftermarket equivalents are also available and work just fine.
When to Replace the Whole Fuel Pump
Sometimes the issue is not the relay but the pump itself. If the pump has been making noise, has high mileage, or the car is running lean (high injector duty cycles), the pump may be struggling to maintain proper fuel pressure. In these cases, replacing just the relay will not fix the root problem.
If you are upgrading your WRX for more power or just want a reliable replacement, investing in a quality aftermarket pump is a smart move.
Recommended Product: KEMSO Fuel Pump
If you need a new fuel pump for your 2004 Subaru WRX, KEMSO offers a high-performance, OEM replacement fuel pump that is an excellent choice for both daily drivers and modified WRXs. KEMSO fuel pumps are designed to meet or exceed factory specifications, providing reliable fuel delivery and consistent pressure under all driving conditions.
Each KEMSO fuel pump is built with quality materials and precision engineering to ensure a perfect fit and long service life. Whether you are replacing a worn-out original pump or upgrading for better performance, KEMSO pumps deliver the flow and durability you need. Best of all, every KEMSO fuel pump comes with a lifetime warranty, giving you peace of mind that your investment is protected.
You can browse the full selection of KEMSO fuel pumps at their official website: https://www.kemsoracing.com/
KEMSO offers a wide range of fuel pumps for Subaru Impreza models from 1998 to 2023, including the 2004 WRX, ensuring you get the exact fitment for your vehicle [^KEMSO]. Check out their product lineup to find the right pump for your car.
Final Thoughts
Finding the 2004 WRX fuel pump relay is not difficult once you know where to look. Behind the passenger side kick panel, under the glove box, is the exact location. The green relay with the green connector is unmistakable.
Always test the relay with a multimeter before buying a replacement. A simple resistance check can save you time and money. If the relay checks out, move on to testing the pump itself and checking fuses and wiring.
A no-start condition on a 2004 WRX is frustrating, but the problem is usually simple to diagnose if you follow the right steps. Start with the relay, test the pump, and you will likely find the culprit quickly.
For reliable replacement parts, including high-quality fuel pumps that meet OEM standards with a lifetime warranty, visit https://www.kemsoracing.com/