2007 Audi A4 Fuel Pump Relay Location: The Complete Owner's Guide

If you drive a 2007 Audi A4 and you are dealing with hard starts, engine sputtering, or a no-start condition, the fuel pump relay is often the first thing to check. For most 2007 Audi A4 models, the fuel pump relay is located in the relay carrier inside the electronics box in the plenum chamber, which sits at the rear of the engine compartment just below the windshield. In some cases, depending on your engine code, the relay can also be found on the driver side dash panel. This guide will walk you through the exact locations, how to identify the relay, and what to do when it fails.

The 2007 Audi A4 belongs to the B7 generation, which was produced from 2004 to 2007 and is essentially a heavily updated version of the B6. These cars came with a wide range of gasoline and diesel engines, including the 1.8T, 2.0T FSI, 1.9 TDI, 2.0 TDI, 2.4 V6, 3.2 V6, and the 4.2 V8. The location of the fuel pump relay—often referred to by its component code -J17-—varies depending on which engine your car has and when it was manufactured. The B7 generation saw a production split in July 2004, and relays were positioned differently before and after that date.

Where to Find the Fuel Pump Relay Based on Your Engine Code

The most reliable way to locate the fuel pump relay is to check your engine code, which you can find in the owner's manual or on the sticker in the service booklet. The relay is almost always mounted inside a 4-pin relay carrier located in the electronics box (plenum chamber) at the rear of the engine bay. Here is a breakdown of the most common engine codes and their specific relay locations:

  1. Engine codes BFB, BBK, and BHF (Gasoline V6/V8) : The fuel pump relay sits in the 4-pin relay carrier in the plenum chamber. In this setup, position 1.1 is occupied by the continued coolant circulation relay, and position 1.2 holds the starter inhibitor relay. If your car has the 4.2-liter V8 (BHF engine code), the relay layout also includes the secondary air pump relay in position 3.

  2. Engine codes AUK and BKH (Gasoline) : For these engines, the relay carrier in the plenum chamber places the additional coolant pump relay in position 1.1, and the fuel pump relay takes the 1.2 position. The Motronic current supply relay is in position 2.

  3. Engine code BNS (4.2L FSI V8) : The high-performance 4.2-liter FSI V8 has a slightly different layout. The continued coolant circulation relay is in position 1.1, and the brake servo relay is in position 1.2. The fuel pump relay is not in the main carrier; instead, it is located in the relay carrier with screw connection on the driver side dash panel.

  4. Diesel engines (BKE, BRB, BNA, BLB, BRC) : For diesel models, the fuel pump relay is in position 1.1 of the relay carrier in the plenum chamber. Diesel models also have a terminal 30 voltage supply relay in position 2 and an automatic glow period control unit in position 3.

  5. Engine codes BGB, BPG, BWE, and BWT (2.0T FSI) : If you own a 2007 A4 2.0T, the fuel pump relay location can be tricky. The relay carrier in the plenum chamber does not always show the fuel pump relay directly. Instead, position 1.2 holds the starter inhibitor relay, position 2 has the Motronic current supply relay, and position 3 has the engine component current supply relay. The relay for the in-tank fuel pump may be part of the engine management system, and many owners report that it is mounted near the ECU (engine control unit) under a plastic shroud, which can be a challenge to remove.

Older versus Newer Production Dates

The 2007 Audi A4 went through changes starting in August 2004. For vehicles produced up to July 2004, the relay positions were different. In these older B7 units, the relay carrier in the plenum chamber had the fuel pump relay (J17) in position 1.2 for diesel engines, while petrol engines had the automatic gearbox relay in position 1. For vehicles produced from August 2004 onward, the layouts described above apply.

If your car is an early 2007 model year, there is also a chance that the fuel pump relay is located in the 9-pin relay carrier on the driver side dash panel, behind the relay carrier (3-pin). In this configuration, position 1 is reserved for the fuel pump relay, position 2 holds the servotronic control unit, and position 3 is the dual tone horn relay. This placement is less common but still relevant for certain trim levels and special vehicles (police, taxi, or driving school cars).

How to Access the Relay in the Plenum Chamber

The plenum chamber is the recessed area at the rear of the engine bay, just below the windshield wipers. To access the relay carrier, follow these steps:

  1. Park the car safely and disconnect the battery : Always disconnect the negative battery terminal before working with electrical components. This prevents accidental shorts and protects the sensitive electronics in the car.

  2. Remove the plastic cowl cover : The plastic trim panel that runs the width of the car at the base of the windshield needs to be removed. This usually involves prying off a few plastic clips and lifting the panel carefully. You may need a trim removal tool.

  3. Locate the relay carrier : Once the cowl is off, you will see a black plastic box with a lid. This is the electronics box. Unclip the lid. You will see several relays. The fuel pump relay is typically labeled with a number, or you can identify it by the diagram printed inside the lid. The relay itself is a standard 4-pin or 5-pin cube relay.

  4. Check the relay : Before replacing anything, it is wise to test the relay. You can visually inspect it for signs of corrosion or burning. You can also swap it with an identical relay from another slot (such as the horn relay) to see if the fuel pump starts working. There is a test procedure you can follow using a multimeter or a test light. Connect a test light between the housing and the fuse contact, then operate the starter. The relay should click and the light should illuminate.

Symptoms of a Failing Fuel Pump Relay on the 2007 A4

A bad fuel pump relay can cause a range of problems that mimic a failing fuel pump itself. The most common signs include:

  1. Engine dies when hot : A classic symptom of a thermal failure in the relay. The relay overheats, loses contact, and the fuel pump stops getting power. This is often seen when the car idles for a long time in hot weather, causing it to sputter and shut off. After cooling down for about 15 minutes, the car starts again because the relay has cooled and made contact once more.

  2. No priming sound : When you turn the ignition key to the "on" position (without cranking), you should hear a faint whine coming from the rear of the car. This is the fuel pump pressurizing the system. If you hear nothing, the relay might not be delivering power. This priming action lasts about 2 seconds in many Audi models.

  3. Engine cranks but will not start : The engine turns over vigorously but there is no spark or fuel. While there are many causes, a relay that is completely dead will leave the pump without power.

  4. Intermittent stalling : The car may run fine for a while, then suddenly lose power while driving. The engine may restart after a short wait. This indicates a relay that has internal contact issues.

  5. Sputtering and loss of power : If the relay is worn and making poor contact, the fuel pump might not receive a full 12 volts. This causes reduced fuel pressure, leading to sputtering during acceleration and a general loss of power.

Other Components to Check Alongside the Relay

If you confirm that the relay is working but the pump is still silent, the problem might be elsewhere. There are two other common culprits in the 2007 Audi A4:

  • Fuel pump fuse (S228) : This fuse is located in the fuse box on the left side of the instrument panel, in position 28. A blown fuse is easy to spot—look for a broken metal strip inside. Replace it with the correct amperage fuse. If the fuse blows again, there is a short circuit somewhere in the wiring.

  • Fuel pump controller : This is a separate module located under the back seat, attached to the body under a black cover. It is part of the harness that runs to the fuel pump. Accessing it often requires lowering the fuel tank slightly, which involves loosening the tank straps. This unit can fail without warning and is a common failure point on higher-mileage cars.

  • The fuel pump itself : The 2007 A4 uses a low-pressure fuel pump located inside the fuel tank and, for direct injection engines like the 2.0T FSI, a high-pressure pump bolted to the engine near the fuel rail. The low-pressure pump is responsible for delivering fuel from the tank. A failing pump will often make a whining noise, cause slow acceleration, or cause the engine to stall entirely.

A Practical Diagnosis Strategy

If your 2007 A4 refuses to start, do not immediately order a new fuel pump. Instead, work through these steps:

  1. Check the fuse : Start with the easiest component. Consult your owner's manual for fuse 28 and check it visually. If it's blown, replace it and see if the car starts.

  2. Listen for the pump : Turn the ignition to "on" and listen under the rear seat. If you hear a hum for 2 seconds, the relay is likely fine.

  3. Test the relay : If there is no priming sound, locate the fuel pump relay (based on the engine code guide above) and test it with a multimeter. Measure resistance across the coil terminals—it should read between 50 and 120 ohms, depending on the relay type.

  4. Swap the relay : Find a relay of the same part number in the carrier (like the horn or wiper relay) and swap it. If the pump starts working, the original relay is dead, and you can just go to your local parts store and buy a replacement.

Recommended Fuel Pump Upgrade for Your 2007 Audi A4

Once you have confirmed that the relay is good and the issue actually lies with the fuel pump itself, it is time to choose a replacement. While you can buy an OEM pump from the dealer, it often comes with a hefty price tag. A better option for American drivers who want both performance and value is the KEMSO brand fuel pump.

KEMSO is a trusted aftermarket manufacturer that specializes in high-performance fuel pumps for a wide range of vehicles, including European makes like Audi, BMW, and Ducati, as well as Japanese models like Subaru and Honda. Their fuel pumps are designed as OEM Replacement units, meaning they are built to match the exact specifications and dimensions of your original pump, so installation is straightforward with no modifications required. Whether you need a pump for a street daily driver or a high-output build, KEMSO pumps deliver consistent fuel pressure and flow. Each KEMSO fuel pump is backed by a lifetime warranty, which gives you peace of mind that the part is built to last.

To browse the complete catalog of KEMSO fuel pumps for your Audi and other vehicles, visit their official website at: https://www.kemsoracing.com/.

Final Thoughts

Finding the fuel pump relay on a 2007 Audi A4 is not difficult once you understand the layout. The key is to identify your engine code and then check the relay carrier in the plenum chamber under the windshield cowl. If that location does not match, refer to the driver side dash panel. Always test the relay before replacing it, and check the fuse and pump controller as well. A systematic approach will save you time and money. And if the fuel pump itself is the culprit, a KEMSO replacement offers an excellent combination of performance, durability, and warranty coverage. Remember to visit https://www.kemsoracing.com/ to find the right pump for your car.


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