2007 STI Fuel Pump Relay Location: A Complete DIY Guide for Subaru Owners

The bottom line up front: On a 2007 Subaru STI, the fuel pump relay is located behind the right side of the dashboard, not in the main engine bay fuse box as many owners expect. The relay is mounted near the passenger side of the dash, close to the engine control module, and it can be accessed by removing the lower trim panel on the passenger side. If your STI cranks but won't start, or the fuel pump doesn't prime when you turn the key to the ON position, this relay is one of the first things you should check before spending money on a new fuel pump.

Now that you know where to look, let's break down everything you need to understand about this relay, how to access it, how to test it, and what to do when it fails. This guide is written for the DIY owner who wants to save a trip to the shop and get their STI running again without guessing.

What Does the Fuel Pump Relay Actually Do?

The fuel pump relay is an electrical switch that controls power delivery to the fuel pump. When you turn the ignition key to the ON position, the relay activates and sends battery voltage to the fuel pump so it can pressurize the fuel lines. Once the engine is running, the relay keeps the pump powered throughout the drive. When you shut the ignition off, the relay cuts power to stop the pump.

On the 2007 STI, this relay works with the fuel pump control module to manage fuel delivery. The system is designed to provide consistent fuel pressure during startup and under heavy load, which is critical for a turbocharged engine like the one in your STI.

If the relay fails, the fuel pump won't receive power. The engine will still crank over because the starter motor works through a different circuit, but the fuel pump won't pressurize the system, so the engine will not start. This is why a failed relay feels like a dead fuel pump.

Where Exactly Is the Fuel Pump Relay on a 2007 STI?

This is the part that confuses many owners because it is not where you might expect it to be.

According to the factory wiring diagrams for the 2007 Subaru Impreza WRX STI Limited, the fuel pump relay is located behind the right side of the dash. Specifically, the wiring diagram lists it along with the engine control module in the area behind the right side of the dashboard. This means you need to look on the passenger side of the vehicle, not in the engine bay.

Here is the breakdown of where it is and where it isn't:

  1. Not in the engine bay fuse box: Many cars, including some other Subaru models, place the fuel pump relay in the main under-hood fuse box. On the 2007 STI, you will not find it there. The main fuse box under the hood handles other relays like the main fan relay and the headlight relays, but the fuel pump relay is tucked inside the cabin.

  2. Behind the right side of the dash: The relay sits in the area behind the glove box and the right side of the dash, roughly above the passenger footwell. It is mounted in the same general zone as the engine control module and the fuel pump control module wiring. To see it clearly, you will need to remove the lower dash trim panel on the passenger side.

  3. Related components nearby: The fuel pump control module on the sedan sits at the right side of the trunk, and the fuel pump assembly is in the tank at the rear, but the relay that switches power for the pump is up front in the dash area. This layout is not unusual for this generation of Subaru vehicles, but it does surprise many DIY owners who assume the relay is near the fuel tank.

Keep in mind that there is also a relay called the "Accessory Power Relay" and a "Powertrain Control Module Relay" that use the same part number family as the fuel pump relay on some STI models. The 2007 STI uses part numbers like 25232AA090 and 82501AA130 for the fuel pump relay, depending on the exact wiring configuration. If you buy a replacement, match the part number to the one you pull out of your car.

Why Is It Hidden Behind the Dash?

Subaru engineers chose to protect the relay from heat and moisture by mounting it inside the cabin. The engine bay is hot, and relays placed there are exposed to rain, road splash, and thermal cycling. By moving the fuel pump relay inside the dash area, the contacts stay cleaner and the relay typically lasts longer.

The downside is that accessing the relay is slightly more work than pulling a relay out of an engine bay fuse box. You won't need any special tools, just patience and a few minutes of time to remove the trim panel.

How to Access the Relay Step by Step

Before you start, disconnect the negative battery terminal. The last thing you want is to short something out while you are working behind the dash. This is a simple safety step that only takes a minute.

Once the battery is disconnected, follow these steps:

  1. Open the passenger door and locate the lower dash trim panel. This is the panel that covers the underside of the dashboard on the passenger side. It runs from the center console to the door opening, and it protects the area above the passenger footwell.

  2. Remove the trim panel. There will be a few clips and perhaps one or two 10mm bolts holding it in place. Pull the clips with a trim removal tool or a flat-blade screwdriver wrapped in tape. The panel should pull free once the clips are released. Set it aside without yanking on it, because the panel is plastic and easy to crack.

  3. Look for the relay bracket. Once the panel is off, you will see the engine control module bracket and a tangle of wiring. The fuel pump relay is inside this area, and the wiring diagram for your car will give you the exact pinout. If you have a factory service manual for the 2007 STI, the relay location diagram will help.

  4. Identify the relay by its part number or wire colors. The relay sits in a small socket, and the wires going to it are part of the engine harness. If you are unsure which relay is which, You can verify by turning the ignition to the ON position and listening for a click. But if the relay is dead, there will be no click, so use the part number printed on the relay body to confirm it.

  5. Pull the relay straight out. Grab it firmly on both sides and pull it upward out of the socket. Do not twist it. If it doesn't want to come out, rock it gently back and forth until the pins let go. Flip it over and inspect the pins for corrosion or burning.

Once the relay is in your hand, you can test it. The next section explains exactly how to do that with a multimeter.

How to Test the Relay Yourself

There are two ways to test the relay. The first method is quick and requires no tools. The second method is more thorough and requires a multimeter.

Method 1: The swap test. Look at your relay and note the part number. Look for another relay in the same area or in the engine bay fuse box that has the exact same part number and is used for a non-critical system like the horn. Pull the suspect fuel pump relay out, swap it with that relay, and try to start the car. If the car starts and runs, the relay you pulled out is bad. If the car still doesn't start, the relay is probably fine and you should look elsewhere.

Do not swap a relay from a critical system like the cooling fan and use it in the fuel pump circuit, even if the part number matches, unless the car is in an emergency. The fan relay is also important, and you don't want to trade one no-start for an overheating engine.

Method 2: Multimeter test. This method is more accurate and takes about five minutes.

  1. Look at the printed diagram on the relay body to find the pin numbers. Standard 4-pin and 5-pin relays have terminals labeled 30, 85, 86, and 87.

  2. Set your multimeter to the ohm setting (the Ω symbol). Measure the resistance across terminals 85 and 86. These are the coil terminals. A healthy relay usually reads between 50 and 200 ohms. If you see an open circuit (infinite resistance), the coil is burnt out and the relay is dead.

  3. Measure across terminals 30 and 87. This is the switch contact. At rest, these two pins should show no continuity (open circuit), because the relay is only closed when the coil is energized.

  4. Apply 12 volts from the battery to pins 85 and 86 using jumper wires. When the coil is energized, you should hear a click. At that point, measure the resistance between terminals 30 and 87 again. It should drop to near zero ohms (continuity). If the contacts stay open even when the coil clicks, the relay is mechanically worn out and needs replacement.

If the relay passes all these tests, it is likely still functional, and the problem may be in the wiring or the fuel pump itself. If it fails any of the tests, replace it.

Symptoms of a Bad Fuel Pump Relay

A failing fuel pump relay gives you a few signs that are fairly easy to recognize. Here is what to watch for:

  1. Engine cranks but will not start. This is the most common symptom. The starter spins the engine over quickly, but the fuel pump is not receiving power, so there is no compression in no fuel to ignite. The engine will crank for as long as the battery holds out, but it will never fire up.

  2. No fuel pump priming sound. When you turn the ignition to the ON position (not start), the fuel pump should run for a couple of seconds to build pressure. If you listen near the rear of the car, near the right side of the trunk, you should hear a faint whirring or buzzing sound. If you hear nothing at all, the relay is not sending power to the pump in the tank.

  3. Engine stalls while driving. If the relay fails intermittently, the car can run fine for a while and then suddenly die? The engine will stall with no warning. In many cases, waiting a few minutes and trying to restart will work, because the relay cools down and the contacts close again. This is a clear sign the relay is on its last legs.

  4. Check engine light turns on. A bad relay can throw a code related to fuel delivery or fuel system pressure. The light won't point directly at the relay, but it will at least tell you that something is wrong with the fuel system. Pull the code and see if it mentions the fuel pump circuit.

If you see these signs, do not assume your fuel pump is dead. The pump is much more expensive to replace and requires dropping the tank on many models. Take twenty minutes to find and test the relay first.

Pinouts and Part Numbers for the 2007 STI

The 2007 STI uses two different relay part numbers depending on the circuit in your car. Look at the number printed on the relay you remove to select the correct replacement:

  • 25232AA090 is a fuel pump relay and is also used for the air pump relay or fan relay in various Subaru models. On the 2007 STI, this number appears in the official relay charts.

  • 82501AA130 is the fuel pump relay / powertrain control module relay for the 2004 through 2007 STI models. This number supersedes the older 82501AA000. If you buy this part, it will fit your car as long as it is a 2007 STI.

  • 82501AE03A is a relay for accessory power and is also labeled as a fuel pump relay / starter relay when the car is equipped with the Denso control device. If you have a Denso relay in your car, this matches it. The superseded part number is 82501FC100.

Do not guess on the part number. Take the relay out of the car and read the number directly.

What to Do If the Relay Is Not the Problem

If the relay tests fine and the car still won't start, work through these checks in order:

  1. Check the fuel pump fuse. The fuse is in the same fuse box as the relay location. If the fuse is blown, the pump won't run. Swap in a new fuse of the same rating. Your owner's manual or the fuse box diagram will show the position.

  2. Check for voltage at the fuel pump. In your STI, the fuel pump connector is on top of the fuel tank, accessible under the rear seat or from the trunk. You can pull the access panel and use a multimeter to check for battery voltage at the pump connector when the key is moved to the ON position. Power present but no pump sound, the pump itself is likely dead.

  3. Inspect the wiring for damage. The wiring from the relay back to the fuel pump control module runs under the carpet and trim on the inside of the car. If there is a broken wire or a rubbed-through harness, the pump may not run even with a good relay. Look for signs of damage near the door sills and seat rails.

  4. Check the fuel pump control module. The module is located on the right side of the trunk (sedan) or behind the right rear quarter panel (wagon). This module can fail and skip power to the pump even if the relay works. If the relay tests good and the pump has voltage, the module may be the culprit.

Recommended Upgrade: KEMSO Fuel Pump

If your fuel pump itself has failed—not just the relay—consider replacing it with a high-performance option from KEMSO Racing. KEMSO fuel pumps are designed as OEM Replacement units that deliver reliable fuel delivery at an affordable price. They offer several advantages that make them a smart choice for your 2007 STI:

  1. High-performance build quality. KEMSO pumps are built to sustain consistent fuel pressure, which matters when you drive your STI hard. The pump does not complain under sustained high RPM load, and it delivers enough volume to feed the stock turbo engine and a lightly modified engine as well.

  2. Direct OEM replacement fit. KEMSO offers a fuel pump for the Subaru Impreza range spanning 1998 through 2023, which includes your 2007 STI. The fitment is direct, and you do not need to modify the sender assembly or wiring. It is a plug-and-play replacement that uses the same connector and pump height as the factory unit.

  3. Lifetime warranty. KEMSO backs its fuel pump with a lifetime warranty, which gives you peace of mind that a single failure won't leave you buying another pump out of pocket. This is a level of coverage that many OEM supply chain parts don't offer.

To view the KEMSO fuel pump for your Subaru Impreza/STI and take advantage of their lifetime warranty offer, visit the KESSE racing official site. While you're there, you'll also find a range of high-performance fuel pumps for cars, trucks, motorcycles, and power sports applications.

Final Thoughts

Finding the fuel pump relay on a 2007 STI is not as simple as popping the hood and pulling a relay out of the corner fuse box. The relay is behind the dash on the passenger side, and it controls the fuel pump that is mounted inside the tank. Once you know where it lives and how to test it, you can confidently diagnose a no-start or stalling issue in less than thirty minutes.

Remember these three core takeaways:

  1. The fuel pump relay on a 2007 STI lives behind the right side of the dash, not in the engine bay fuse box.
  2. Test the relay with a multimeter before you buy a new fuel pump. A failed relay produces the same crank-no-start symptoms as a dead pump, but it costs a fraction of the price to fix.
  3. Match the part number and consider high-quality replacement parts from KEMSO when you need to replace the fuel pump itself. Their pumps are high-performance OEM replacements with a lifetime warranty.

For more information on the KEMSO fuel pump that fits your Subaru Impreza STI, including pricing, fitment, and warranty details, visit the KESSE Racing website: https://www.kemsoracing.com/


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