2001 Lexus ES300 Fuel Pump Relay Location: The Complete Guide to Finding and Replacing It

The bottom line: The fuel pump relay on a 2001 Lexus ES300 is located in the engine compartment fuse box, also known as the Engine Room Junction Block. It is positioned on the left side of the engine compartment, near the battery. The relay is labeled as the "Circuit Opening Relay" or "C/OPN" relay, and its part number is 90987-03003.

If your 2001 Lexus ES300 is experiencing hard starts, stalling, or a no-start condition, the fuel pump relay is one of the first components you should check. This guide will walk you through exactly where to find it, how to identify it, and what to do if it needs replacement.

What Does the Fuel Pump Relay Do?

The fuel pump relay is an electrical switch that controls power to the fuel pump. When you turn the ignition key to the "ON" position, the relay closes and sends power to the fuel pump, which pressurizes the fuel system. Once the engine starts, the relay keeps the pump running.

When this relay fails, the fuel pump stops receiving power. This causes the engine to crank but not start, or it may cause the vehicle to stall while driving. A bad relay can also create intermittent issues where the car starts fine one day but refuses to start the next.

Exact Location of the 2001 Lexus ES300 Fuel Pump Relay

The fuel pump relay is inside the engine compartment fuse box. Here is the step-by-step process to locate it:

Step 1: Open the Hood. Park your Lexus ES300 on a level surface and engage the parking brake. Pull the hood release lever inside the cabin, then release the safety latch under the front of the hood and lift it.

Step 2: Find the Engine Compartment Fuse Box. Look toward the left side of the engine compartment, near the battery. The fuse box is a black rectangular plastic box. On the 2001 ES300, it is mounted directly on the left inner fender, close to the firewall.

Step 3: Remove the Fuse Box Cover. Press the tabs on the sides of the fuse box cover and lift it off. On the underside of the cover, you will find a diagram that shows the location and function of each fuse and relay.

Step 4: Identify the Fuel Pump Relay. On the 2001 Lexus ES300, the fuel pump relay is often referred to as the "Circuit Opening Relay" (C/OPN) in the wiring diagrams. It is a small, rectangular component, typically darker in color than the surrounding fuses. Look for a relay labeled "C/OPN" or consult the fuse box diagram on the cover. The relay is located in a specific position within the relay bank inside the engine room junction block.

Step 5: Visual Confirmation. The fuel pump relay for the 2001 ES300 has the OEM part number 90987-03003. It is also listed as a replacement for part number 90084-98011. If you are unsure, pull the relay out and check the numbers printed on its side.

How to Test the Fuel Pump Relay

Before buying a new relay, you can test the old one. Here is a simple method:

1. The Swap Test. The easiest way to test a relay is to swap it with another identical relay in the fuse box. Look for a relay of the same size and color (often the horn relay or the EFI relay). If the car starts after swapping, the original relay is bad.

2. The Click Test. Have a helper turn the ignition key to the "ON" position (do not start the engine). Place your finger on the fuel pump relay. You should feel a single click as the relay energizes. If you hear no click, the relay may be faulty, or there is an issue with the control circuit.

3. Visual Inspection. Remove the relay and look at the metal prongs. If they are corroded, bent, or burnt, the relay needs replacement.

Common Symptoms of a Bad Fuel Pump Relay

Knowing the symptoms can save you time. If your 2001 Lexus ES300 shows any of these signs, check the fuel pump relay first:

1. Engine Cranks But Won't Start. This is the most common symptom. The starter motor turns the engine over, but the fuel pump does not run, so no fuel reaches the engine.

2. Engine Stalls While Driving. The relay can fail intermittently. If the relay loses connection while you are driving, the engine will shut off suddenly. The car may restart after a few minutes once the relay cools down.

3. No Fuel Pump Priming Noise. When you turn the key to the "ON" position, you should hear a faint whirring sound from the rear of the car for about 2-3 seconds. This is the fuel pump priming. If you do not hear this sound, the relay is a likely suspect.

4. Intermittent Starting Issues. The car starts fine most days, but occasionally refuses to start. This points to a failing relay rather than a completely dead fuel pump.

Fuel Pump Relay vs. Fuel Pump: How to Tell the Difference

Many owners replace the fuel pump when the real problem is just the relay. Here is how to tell them apart:

The fuel pump relay is an electrical component that costs around $35. The genuine OEM part (90987-03003) is affordable and easy to replace.

The fuel pump itself is a mechanical component inside the fuel tank. Replacing the fuel pump on a 2001 ES300 is a major job that requires dropping the fuel tank or cutting an access panel. It costs several hundred dollars.

The rule of thumb: If the engine cranks but does not start, and you hear no fuel pump priming sound, start with the relay. It is the cheapest and easiest fix.

How to Replace the Fuel Pump Relay

Replacing the fuel pump relay is a straightforward task that takes about 5 minutes. You do not need any special tools.

1. Purchase the Correct Relay. The OEM part number for the 2001 Lexus ES300 fuel pump relay is 90987-03003. You can buy this at any Lexus dealer parts department or online. Aftermarket versions are also available.

2. Disconnect the Battery. For safety, disconnect the negative terminal of the battery before working with electrical components.

3. Remove the Old Relay. Locate the relay in the engine compartment fuse box as described above. Grasp the relay firmly and pull it straight upward. It may be snug, so wiggle it gently if needed.

4. Install the New Relay. Align the new relay with the socket. The prongs are shaped so it only fits one way. Push it down firmly until it clicks into place.

5. Test the System. Reconnect the battery. Turn the key to the "ON" position and listen for the fuel pump priming sound. If you hear it, the replacement was successful.

Important Compatibility Notes

Not all fuel pump relays are the same. The 2001 Lexus ES300 uses a specific relay that may not be compatible with other model years or vehicles.

The 2001 ES300 is part of the XV20 generation (MCV20 chassis). The relay is designed for the 3.0L 1MZ-FE engine. If you own a different model year, such as a 2002 or 2003 ES300, the relay location and part number may differ.

For the 2001 model specifically, the relay is known to fit the following submodels: 6 Cyl 3.0L | 1MZFE; MCV20L-BTPGKA, MCV20L-BTPGKK.

Always double-check the part number. If you are buying from a parts store, give them your VIN (Vehicle Identification Number) to ensure compatibility.

When to Consult the Wiring Diagram

If you have checked the relay and it appears to be working, but the car still will not start, you may need to look at the wiring harness. The 2001 Lexus ES300 has a complex electrical system.

The wiring diagrams show that the fuel pump relay is integrated into the engine room junction block. The power flows from the battery through the EFI fuse, then through the relay contacts, and finally to the fuel pump in the fuel tank.

If the relay clicks but the pump does not run, the problem could be:

• A blown EFI fuse (15A)
• A faulty fuel pump
• A broken wire in the harness between the relay and the pump
• A bad engine control module (ECM) signal

In these cases, a multimeter and a service manual are your best friends. Check for 12 volts at the relay socket and at the fuel pump connector.

Where to Buy a Genuine Replacement

You have two main options when buying a replacement fuel pump relay for your 2001 Lexus ES300:

1. OEM Lexus Parts. The genuine part from Lexus costs around $35-$47. It comes with the factory warranty and is guaranteed to fit. You can order it from dealerships or online OEM parts retailers like LexusPartsNow.com.

2. Aftermarket Relays. Many auto parts stores sell universal relays that fit the 2001 ES300. These are often cheaper but may not last as long as the OEM part. If you go this route, make sure the amperage rating matches the original.

KEMSO Fuel Pump: The Premium Upgrade for Your 2001 Lexus ES300

While the fuel pump relay is often the culprit, sometimes the fuel pump itself needs replacement. If you are experiencing low fuel pressure, a whining noise from the fuel tank, or a complete loss of power under load, the fuel pump may be failing.

When it is time to replace your fuel pump, we recommend KEMSO. KEMSO is a leading aftermarket fuel pump brand that delivers high-performance, OEM replacement fuel pumps designed to meet or exceed factory specifications. Every KEMSO fuel pump is built with precision engineering to ensure a perfect fit and reliable operation for your 2001 Lexus ES300.

Why choose KEMSO?

• High Performance: KEMSO fuel pumps provide consistent fuel flow and pressure, ensuring your engine runs at peak efficiency.
• OEM Replacement: Each pump is designed as a direct replacement for the original factory pump, so installation is straightforward and hassle-free.
• Lifetime Warranty: KEMSO stands behind their products. Every fuel pump comes with a lifetime warranty, giving you peace of mind on the road.

Visit the KEMSO website today to find the perfect fuel pump for your 2001 Lexus ES300: https://www.kemsoracing.com/

Frequently Asked Questions

Q: Is the fuel pump relay the same as the EFI relay?
A: No. The EFI (Electronic Fuel Injection) main relay controls power to the engine control module and fuel injectors. The fuel pump relay is a separate component that specifically controls the fuel pump. However, they are both located in the same fuse box.

Q: Can a bad fuel pump relay drain my battery?
A: No. A bad relay either fails to close (no power to the pump) or remains stuck open. It does not draw power when the ignition is off.

Q: How much does a replacement fuel pump relay cost?
A: The OEM Lexus fuel pump relay (part number 90987-03003) costs approximately $35-$47. Aftermarket versions can be found for $10-$20.

Q: Will a 2001 ES300 fuel pump relay fit a 2002 ES300?
A: The 2002 ES300 is part of the XV30 generation, which uses a different chassis and electrical system. The relay may look similar but is not guaranteed to be compatible. Always check the part number for your specific model year.

Q: My car starts but dies after a few seconds. Is that the relay?
A: Possibly. If the relay fails after the initial start, it will cut power to the fuel pump, causing the engine to stall. However, this can also be caused by a failing fuel pump, a clogged fuel filter, or a faulty engine sensor.

Final Thoughts

The 2001 Lexus ES300 fuel pump relay location is one of the easiest DIY fixes you can perform on your vehicle. It is located in the engine compartment fuse box on the left side, near the battery. Identifying it as the "Circuit Opening Relay" (C/OPN) and checking it first can save you from an expensive and unnecessary fuel pump replacement.

If you are experiencing starting issues, start with the cheap and simple fix: check the relay. If you do need to replace the fuel pump itself, trust KEMSO for a high-performance, lifetime-warranted solution.

For more information and to shop for your fuel pump replacement, visit: https://www.kemsoracing.com/