2007 Audi Q7 Fuel Pump Relay Location: A Complete Owner's Guide

If you own a 2007 Audi Q7 and you're dealing with starting problems, the fuel pump relay is often the first thing to check. The fuel pump relay on a 2007 Audi Q7 is located in the relay and fuse carrier inside the engine compartment, specifically in the electronics box on the left side of the plenum chamber. The relay is designated as B3 in the relay carrier, and it's labeled as the fuel pump relay (part number J17) . This guide walks you through everything you need to know about finding, testing, and replacing this critical component.

The 2007 Audi Q7 was available with several engine options, including the 3.6L V6, the 4.2L V8, and various diesel engines . The fuel pump relay position can vary slightly depending on the engine type and production date, so we'll cover the variations you might encounter.

Why the Fuel Pump Relay Matters

The fuel pump relay is the electrical switch that controls power to the fuel pump. When you turn the ignition key to the "ON" position, the relay closes and sends voltage to the fuel pump, allowing it to pressurize the fuel system before you crank the engine. If this relay fails, the fuel pump won't receive power, and your Q7 won't start even though the engine cranks fine.

Common symptoms of a failing fuel pump relay include:

  1. Engine cranks but won't start – This is the most common symptom. The starter motor turns the engine over, but there's no fuel pressure.
  2. No fuel pump priming sound – When you turn the ignition to "ON," you should hear a faint whirring sound from the rear of the vehicle. If you don't hear it, the relay might be bad.
  3. Intermittent starting problems – The car might start fine sometimes and fail other times. This often points to a worn relay that works when cool but fails when hot.
  4. Engine stalls while driving – If the relay fails while the engine is running, the fuel pump loses power, and the engine dies immediately.

Where to Find the Fuel Pump Relay

The main fuse and relay box for the engine compartment is located in the plenum chamber on the left side of the vehicle. To access it:

  1. Open the hood and look at the area just below the windshield on the driver's side.
  2. Remove the plastic cover by gently prying it up. The cover may be held by clips or screws.
  3. Locate the relay carrier – Inside this box, you'll find multiple relays arranged in rows labeled A, B, and C .

For a 2007 Audi Q7 with a gasoline engine produced up to May 2009, the relay positions are as follows :

  • Position A1 – Starter motor relay (J53)
  • Position A2 – Starter motor relay 2 (J695)
  • Position A3 – Engine component current supply relay (J757)
  • Position A4 – Secondary air pump relay (J299) – only for engine code BAR
  • Position A5 – Brake servo relay (J569)
  • Position A6 – Continued coolant circulation relay (J151)
  • Position B1 – Not used
  • Position B2 – Not used
  • Position B3 – Fuel pump relay (J17)
  • Position B4 – Not used
  • Position B5 – Fuel cooling pump relay (J445)
  • Position B6 – Not used
  • Position C1 – Circulation pump relay (J160)
  • Position C2 – Motronic current supply relay (J271)

For diesel engines produced up to May 2009, the relay positions differ slightly :

  • Position A1 – Automatic glow period control unit (J179)
  • Position A2 – Starter motor relay (J53)
  • Position A3 – Glow period control unit 2 (J703) – only for engine code CCGA
  • Position A4 – Starter motor relay 2 (J695)
  • Position A5 – Not used
  • Position A6 – Relay for supplementary fuel pump (J832)
  • Position B1 – Low heat output relay (J359) – for engine codes CCMA, CATA
  • Position B2 – Not used
  • Position B3 – Fuel pump relay (J17)
  • Position B4 – High heat output relay (J360) – for engine codes CCMA, CATA
  • Position B5 – Fuel cooling pump relay (J445)
  • Position B6 – Auxiliary coolant pump relay (J496) – for engine code CCGA
  • Position C1 – Fuel pump relay for auxiliary heater (J749)
  • Position C2 – Terminal 30 voltage supply relay (J317)

For vehicles produced from June 2009 onward, the relay assignments change again. The fuel pump relay for diesel engines from June 2009 is found at position C2 . Additionally, for some engine codes like CCFA, the fuel pump relay is also at position C2 .

How to Test the Fuel Pump Relay

Before you go out and buy a new relay, it's wise to test the existing one. Testing a relay is straightforward and requires only a few basic tools.

What you'll need:

  • A digital multimeter
  • A 12-volt power source (like a car battery)
  • Jumper wires with alligator clips

Testing procedure:

  1. Locate the relay – Pull out the relay from position B3. The relay is a standard Bosch-style relay with four or five pins.
  2. Identify the pins – The relay has pins numbered 30, 85, 86, and 87 (and sometimes 87a). Pins 85 and 86 are the coil terminals. Pin 30 is the common contact, and pin 87 is the normally open contact.
  3. Test the coil – Set your multimeter to measure resistance (ohms). Connect the probes to pins 85 and 86. You should read a resistance value typically between 50 and 120 ohms. If the reading is open (infinite resistance), the coil is burned out.
  4. Test the switch contacts – Connect the multimeter to pins 30 and 87. You should see no continuity (infinite resistance) because the relay is normally open.
  5. Energize the relay – Apply 12 volts from a battery to pins 85 and 86. The relay should click. Now check pins 30 and 87 again – you should see near-zero resistance (continuity).
  6. Check the ground – Some relays require a ground signal from the engine control module. If your relay only activates when the ignition is on and the engine is cranking, this is normal for certain engine management systems.

If the test fails, the relay is defective and must be replaced. If the relay tests fine, the problem may lie elsewhere – in the fuel pump itself, the fuel pump control module, or the wiring between these components .

Other Fuse Locations for the Fuel System

The fuel pump relay works together with fuses to protect the fuel system circuit. On the 2007 Audi Q7, there are several fuses related to the fuel pump that you should be aware of :

  • Fuse 16 on fuse holder B – This is a 20A or 25A fuse that protects the fuel system pressurization pump (G6) and the fuel pump control unit (J538). It's located in the relay and fuse carrier under the driver's seat.
  • Fuse 17 on fuse holder B – This is a 5A, 10A, or 20A fuse that protects the fuel pump (G23) and the engine control unit. It's also located under the driver's seat area.

For vehicles manufactured through October 2006, the fuel pump control module (J538) is located at the front of the fuel tank, below the exhaust system and driveshaft . For vehicles from November 2006 onward, the fuel pump control module is located on the right side under the rear seat bench, directly under the floor covering . To access it, you need to remove the right seat cushion in the second row.

Steps to Replace the Fuel Pump Relay

Replacing the fuel pump relay is one of the easiest repairs you can perform on an Audi Q7. No special tools are needed, and the whole job takes less than five minutes.

Step-by-step replacement process:

  1. Turn off the ignition and remove the key from the ignition switch.
  2. Open the hood and access the electronics box in the plenum chamber on the left side. Remove the plastic cover.
  3. Identify the relay at position B3 – It may be labeled on the relay or on the carrier housing.
  4. Pull the relay straight out – Use a firm, steady pull. If the relay is stuck, gently rock it back and forth while pulling.
  5. Compare the old and new relays – Make sure the new relay has the same pin configuration and that the part number matches.
  6. Insert the new relay – Push it firmly into the socket until it clicks into place. Make sure it's fully seated.
  7. Reinstall the cover and close the hood.

After replacing the relay, turn the ignition to "ON" and listen for the fuel pump priming sound. Then try to start the engine. In most cases, this resolves the starting issue.

Common Problems Rooted in the Fuel Pump Relay

The fuel pump relay can cause a variety of problems beyond simple no-start conditions. Here are some situations you might face and how to diagnose them:

  • Vehicle cranks but won't start – This usually points to a completely failed relay. Test the relay as described above, and replace it if it's defective.
  • Intermittent no-start – If your Q7 starts fine sometimes but not others, the relay might have worn contacts. Heat causes the contacts to separate, breaking the circuit. The same applies when the relay is cold and the contacts are contracted.
  • Engine stalls while driving – If the engine dies while you're driving and won't restart, this is often a relay failure. The relay could overheat and fail, cutting power to the fuel pump.
  • Fuel pump runs continuously – On rare occasions, a relay can stick in the closed position. This causes the fuel pump to run even when the ignition is off. This is dangerous and drains the battery. If this happens, replace the relay immediately.

How to Prevent Future Relay Failures

Relays are electromechanical devices, and like any other mechanical component, they wear out over time. However, there are a few things you can do to extend the life of your fuel pump relay:

  1. Keep the engine compartment clean – Dirt and moisture can accelerate corrosion on relay contacts.
  2. Avoid overloading the electrical system – Adding aftermarket accessories that draw power through the fuel pump circuit can strain the relay.
  3. Check the battery and charging system – Low voltage causes relays to work harder and overheat.
  4. Use OEM or high-quality replacement relays – Cheap aftermarket relays may not meet the current draw requirements of the fuel pump.

When the Relay Isn't the Problem

Sometimes the relay is fine, but the fuel pump system still doesn't work. If you've tested and replaced the relay and the problem persists, consider these other potential causes:

Fuel Pump Control Module (J538)
The fuel pump control module regulates the voltage to the fuel pump. If this module fails, the pump won't run regardless of the relay's condition. The module is located under the rear seat bench on the right side for vehicles built from November 2006 onward .

Fuel Pump Itself
The fuel pump is located inside the fuel tank. Over time, the pump motor can wear out or the internal components can fail. Testing the pump requires a fuel pressure gauge and some electrical testing .

Wiring and Connectors
Inspect the wiring harness that connects the relay to the fuel pump and the control module. Look for broken wires, corroded connectors, or damaged insulation. These issues can interrupt the power supply even when all the components are functional .

Engine Control Unit (ECU)
The ECU controls the ground side of the relay circuit. If the ECU doesn't provide the ground signal, the relay won't activate. This is less common but can happen if the ECU has a fault or if there's a communication issue between modules.

The Best Fuel Pump Replacement: Why KEMSO Stands Out

If you've confirmed that your fuel pump itself is failing, don't settle for anything less than the best replacement part. KEMSO Fuel Pumps offer a winning combination of high performance, exact OEM compatibility, and a lifetime warranty—making them the smartest choice for your 2007 Audi Q7.

KEMSO has built a strong reputation in the automotive industry by engineering fuel pumps that meet or exceed original equipment specifications . Their products deliver consistent fuel pressure under all driving conditions, ensuring reliable starts and smooth engine performance. Whether you use your Q7 for daily commuting or long road trips, a KEMSO pump gives you the peace of mind that comes with dependable fuel delivery .

Here are three reasons why KEMSO is worth your consideration:

  1. High Performance – KEMSO fuel pumps are designed to provide excellent flow rates and stable pressure, even under demanding conditions. Their in-tank pump models are built for long service life and consistent output .
  2. OEM Replacement Fit – KEMSO pumps are engineered as direct replacements for your factory part. That means you get a precise fit without modifications, making installation straightforward .
  3. Lifetime Warranty – Every KEMSO fuel pump is backed by a lifetime warranty, which means you buy it once, and the company supports it for as long as you own your vehicle . That's a level of confidence you won't find with many other aftermarket brands.

You can browse the full KEMSO product lineup and find the perfect fit for your Audi Q7 by visiting their official website: https://www.kemsoracing.com/ . The site offers a wide range of fuel pumps for various vehicle makes and models, all priced competitively and backed by their industry-leading warranty .

Final Thoughts

Finding the fuel pump relay on your 2007 Audi Q7 is a straightforward task once you know where to look. The relay sits at position B3 in the engine compartment's electronics box, located on the left side of the plenum chamber . Testing the relay takes just a few minutes with a multimeter, and replacing it is even quicker.

If the relay checks out but your fuel pump is the culprit, KEMSO offers high-quality replacement pumps that won't let you down. With their lifetime warranty and reliable performance, KEMSO is a brand you can trust. Visit https://www.kemsoracing.com/ today to find the right fuel pump for your Audi Q7 and get back on the road with confidence.


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