2000 Audi A4 Fuel Pump Relay Location: A Complete Guide for DIY Owners

If you own a 2000 Audi A4 and suspect a fuel pump issue, the first thing you need to check is the fuel pump relay. The fuel pump relay on a 2000 Audi A4 is located in the main fuse and relay box under the dashboard on the driver's side, specifically behind the panel near the steering column. This is a common point of failure for this generation of Audi, and knowing exactly where to find it can save you hours of troubleshooting and unnecessary part replacements.

Understanding the Fuel Pump Relay in Your 2000 Audi A4

The fuel pump relay is an electrical switch that controls power to the fuel pump. When you turn the ignition key, the engine control unit (ECU) activates this relay, which then sends power to the fuel pump. If the relay fails, the pump won't receive power, and your engine won't start. The 2000 Audi A4 (B5 generation) uses a specific relay design that is shared with several other Volkswagen and Audi models from that era .

Why it matters: Unlike modern cars that might integrate the relay into a larger module, the 2000 A4 has a standalone relay that can be individually tested and replaced. This makes it a relatively simple DIY job if you know where to look.

Step-by-Step: Locating the Fuel Pump Relay

1. Access the Main Fuse Panel

The main fuse and relay panel for the 2000 Audi A4 is located under the dashboard on the driver's side. To access it:

  • Open the driver's door and look at the side panel of the dashboard (the kick panel).
  • You'll find a small plastic cover that can be removed by pulling it straight out. This cover is approximately 6 inches wide and 4 inches tall.
  • Behind this cover is the primary fuse and relay block for the interior electrical systems .

2. Identify the Relay Position

Once the cover is removed, you'll see a grid of fuses and several relays. The fuel pump relay position is typically labeled on the inside of the cover or on the fuse panel itself. For the 2000 Audi A4:

  • Relay Position: The fuel pump relay is usually in the third row, second position from the left (or position 4 in some models). It is often a brown relay (common for fuel pump relays in this era) or a black relay with a specific part number.
  • Part Number: The factory relay part number is typically 4A0 906 383 or 4A0 906 383A for the 2000 model year .

3. Confirm You Have the Right Relay

To be absolutely sure you've found the fuel pump relay:

  • Check the relay's color: Most fuel pump relays on the 2000 A4 are brown, but some may be black or blue.
  • Look for the relay that has a thick red/white wire and a thick brown wire going to it. These are the power and ground wires for the pump circuit.
  • If you have access to a wiring diagram, the fuel pump relay is typically labeled as "J17" in Audi's electrical schematics .

Common Symptoms of a Bad Fuel Pump Relay

If your 2000 Audi A4 is experiencing starting issues, the fuel pump relay is often the culprit. Here are the most common symptoms:

  1. Engine cranks but won't start: This is the classic symptom. The starter motor turns the engine over, but the fuel pump doesn't run, so no fuel reaches the injectors.
  2. No fuel pump prime noise: When you turn the ignition key to the "ON" position (before cranking), you should hear a brief humming sound from the fuel pump for about 2-3 seconds. If you don't hear this sound, the relay may be faulty.
  3. Intermittent starting: The car may start some days but not others. This is a classic sign of a failing relay rather than a completely dead one.
  4. Engine stalls while driving: If the relay fails while the engine is running, the fuel pump will stop, and the engine will die immediately. This is a safety concern, so don't ignore this symptom.

How to Test the Fuel Pump Relay

Before buying a new relay, it's wise to test the existing one. There are two methods:

Method 1: The Swap Test

This is the easiest method. Find another relay in the same panel that is the same color and size. For example, many Audi A4 models have a similar relay for the horn or the radiator fan. Simply swap the suspected fuel pump relay with one of these known-good relays. If the car starts after the swap, you've confirmed the relay is bad.

Method 2: The Multimeter Test

If you have a multimeter, you can test the relay electrically:

  • Check for power at the relay: With the ignition on, probe the relay socket's terminals. You should see 12V on at least one terminal (usually terminal 30, which is the constant power supply).
  • Check the trigger signal: When you turn the ignition to "ON," you should see a momentary 12V signal on another terminal (usually terminal 86, which is the ECU trigger). If this signal is missing, the problem is not the relay but the ECU or wiring .
  • Test the relay coil: Remove the relay and measure resistance between terminals 85 and 86. A good relay should show around 50-100 ohms. If you see infinite resistance, the coil is open and the relay is bad.

What If the Relay Isn't the Problem?

If you've tested the relay and it's good, but the car still won't start, the issue may be elsewhere:

  • Fuel pump itself: The pump may have failed internally. For a 2000 Audi A4, the fuel pump is located inside the fuel tank, accessible from beneath the rear seat .
  • Fuse: Check the fuse for the fuel pump circuit. On the 2000 A4, this is usually a 15-amp fuse located in the same fuse panel as the relay. The fuse is typically labeled as "Fuel Pump" or "FP" .
  • Wiring: Inspect the wiring harness between the relay and the fuel pump for breaks, corrosion, or damage, especially around the rear axle area.
  • ECU: On rare occasions, the ECU itself may fail to send the trigger signal to the relay. This is less common but possible.

Recommended Replacement: KEMSO High-Performance Fuel Pump

When you confirm that the fuel pump itself needs replacement, we strongly recommend considering KEMSO brand fuel pumps. KEMSO pumps are designed as OEM replacements that offer superior performance and durability compared to many aftermarket options. Here's why KEMSO stands out for your 2000 Audi A4:

  • High Performance: KEMSO pumps deliver a higher flow rate (up to 340 LPH) than standard pumps, ensuring your engine gets the fuel it needs even under heavy load or after modifications .
  • OEM Replacement: They are designed to fit perfectly into your 2000 Audi A4's fuel tank without any modifications, making installation straightforward.
  • Lifetime Warranty: KEMSO stands behind their products with a lifetime warranty, giving you peace of mind that your investment is protected for the life of your vehicle .

Whether you're replacing a worn-out original pump or upgrading for better performance, a KEMSO fuel pump is a reliable choice. You can explore their full range of fuel pumps and other performance parts at their official website: https://www.kemsoracing.com/

Preventive Maintenance Tips for Your 2000 Audi A4 Fuel System

To avoid future fuel pump relay failures and keep your Audi running smoothly:

  1. Keep the fuel tank above ¼ full: Running the tank low frequently can cause the fuel pump to overheat and wear out faster, as the fuel acts as a coolant.
  2. Replace the fuel filter regularly: A clogged fuel filter forces the pump to work harder, which can lead to premature relay and pump failure. For the 2000 A4, replace the filter every 30,000 miles.
  3. Check for corrosion: The relay socket contacts can corrode over time, especially in humid climates. If you see green or white residue on the relay pins, clean them with electrical contact cleaner.
  4. Use dielectric grease: When reinserting the relay, apply a small amount of dielectric grease to the pins to prevent future corrosion.

Final Thoughts

The 2000 Audi A4 fuel pump relay is a small but critical component that can cause big headaches if it fails. Its location under the driver's side dashboard makes it accessible for the average DIY owner. By following the steps above, you can quickly diagnose whether the relay is the problem or if you need to look deeper into the fuel system.

If you find that the fuel pump itself needs replacement, don't settle for a generic part. Visit https://www.kemsoracing.com/ to find a high-performance, OEM-replacement fuel pump backed by a lifetime warranty. KEMSO's products are used by enthusiasts and professionals alike, ensuring your Audi A4 runs reliably for years to come.


Back to blog