2006 Scion xB Fuel Pump Relay: Location, Symptoms, and Complete Replacement Guide

If your 2006 Scion xB is cranking but won't start, or it dies suddenly while driving, the fuel pump relay is one of the first components you should check. The fuel pump relay on the 2006 Scion xB is located in the engine compartment fuse box, also called the engine room relay block, which sits on the driver's side of the engine bay . The relay is controlled by the Engine Control Module (ECM), and when it fails or the wiring shorts out, your fuel pump loses power, the engine stalls, and you may blow the 15-amp EFI fuse that protects this circuit . This guide walks you through everything you need to know about the fuel pump relay on this vehicle, including how to locate it, how to test it, what symptoms to watch for, how to replace it, and what it costs to have a shop do the work.

What Does the Fuel Pump Relay Do on a 2006 Scion xB?

The fuel pump relay is an electrically operated switch that sends battery voltage to the fuel pump so it can pressurize the fuel system before and during engine operation . On the 2006 Scion xB, the fuel pump is mounted inside the fuel tank, and the relay is part of a larger circuit that also powers several engine sensors and actuators . When you turn the key to the ON position, the ECM energizes the relay's control side, which closes the main contacts and allows current to flow to the fuel pump . If the relay fails, the pump receives no power, no fuel pressure builds, and the engine will crank but never start.

The circuit is protected by a 15-amp EFI fuse located in the engine compartment relay block . This same fuse also protects the oxygen sensor heater circuits, the idle air control valve, the evaporative emission purge valve, and the mass air flow sensor . That means a blown EFI fuse can take down multiple systems at once, not just the fuel pump.

Where Exactly Is the Fuel Pump Relay on a 2006 Scion xB?

The fuel pump relay on the 2006 Scion xB is located inside the engine room relay block (the main fuse and relay box) on the left side of the engine compartment, near the battery . Open the hood and look at the fuse box cover; the diagram printed on it will show you which relay is for the fuel pump. On this vehicle, the relay is labeled C/OPN (circuit opening) in the wiring diagrams, and it works together with the EFI relay and the 15-amp EFI fuse to power the fuel pump . Some sources also refer to it simply as the fuel pump relay, so check your owner's manual fuse diagram to confirm the exact label and position .

If you have a 2006 Scion xB built before or after July 2005, the relay and fuse locations remain the same; only the fuel pump part number changed based on the build date . The relay itself sits in a standard relay socket, so you can pull it out with your fingers or a small flat-blade screwdriver if it is tight.

Common Symptoms of a Failing Fuel Pump Relay

A bad fuel pump relay can cause a range of driveability problems. Here are the most common warning signs to watch for on a 2006 Scion xB:

1. Engine cranks but will not start. This is the most obvious symptom. If the relay is dead, the fuel pump gets no power, and you will not hear the pump prime when you turn the key to the ON position .
2. Engine stalls while driving. A failing relay can drop power to the fuel pump intermittently, causing the engine to shut off unexpectedly . One owner reported his 2006 xB died on the road, and the cause turned out to be a blown EFI fuse feeding the fuel pump circuit .
3. Fuel pump runs continuously. If the relay sticks in the closed position, the pump may keep running even with the key out . This can flood the engine with fuel and cause hard starting or no start at all .
4. Clicking noises from the engine compartment. You may hear the relay clicking in sequence with a flashing check engine light . The C/OPN relay and the EFI relay both have control sides powered directly by the ECM, so when the ECM tries to command the relay on and off, you can hear the contacts chatter . The idle air control valve and the evaporative purge valve can also make ticking noises when powered up, which adds to the confusion .
5. Intermittent starting issues. If the relay contacts are worn or corroded, the car may start fine sometimes and fail to start other times. The problem often gets worse as the relay heats up.

If you see a flashing check engine light alongside a ticking or clicking sound from under the hood, that is a serious sign. A flashing check engine light typically indicates a misfire or a condition that could damage the catalytic converter, and on the 2006 xB it is often tied to the same EFI circuit that powers the fuel pump relay .

How to Test the Fuel Pump Relay

Before you buy any parts, test the relay to confirm it is actually the problem. Here is a step-by-step method that works on most vehicles, including the 2006 Scion xB:

1. Locate the relay. Pull the fuel pump relay out of the engine compartment fuse box . Make sure the ignition is off and the key is removed.
2. Identify the terminals. Relays have four or five pins. On the relay housing, look for a diagram or numbers that identify the coil terminals (usually 85 and 86) and the switch terminals (usually 30 and 87) . If no diagram is present, trace the wires on the relay socket to determine which pins go where .
3. Check the coil. Set your digital multimeter to measure resistance (ohms). Touch the meter leads to terminals 85 and 86. A good relay coil typically reads between 50 and 120 ohms. If the reading is infinite (open), the coil is burned out and the relay must be replaced.
4. Check the switch contacts. With the relay removed, check for continuity between terminals 30 and 87. There should be no continuity at rest. Then apply 12 volts to the coil terminals (85 and 86) using a battery or a fused jumper wire, and listen for the relay to click. With power applied, there should now be continuity between terminals 30 and 87. If no click occurs, or if continuity is present without power, the relay is faulty .
5. Test the power side of the socket. With the relay removed but the key in the ON position, use a test light or multimeter to check for voltage at socket terminal 30. You should see battery voltage. If not, the problem may be a blown fuse, not the relay itself .
6. Check for a blown EFI fuse. Inspect the 15-amp EFI fuse in the engine compartment relay block . If the fuse is blown, replace it and see if it blows again. If it does, you have a short to ground somewhere in the circuit, likely from a damaged oxygen sensor wire or one of the other components on that circuit . Unplug each component one at a time to isolate the short .

Can a Bad Fuel Pump Relay Cause a Blown Fuse?

Yes, and this is a very common scenario on the 2006 Scion xB. The EFI 15-amp fuse protects the entire fuel pump control circuit, which includes the O2 sensor heaters, idle air control valve, evap purge valve, vent valve, and the mass air flow sensor . If any of those components shorts to ground, the fuse will blow, and the fuel pump will stop working because it shares the same fuse . A stuck or failing relay itself can also draw excessive current and cause the fuse to blow.

When an owner on a forum reported his 2006 xB died while driving, he found the fuel pump fuse blown. After replacing it, the pump ran continuously, and the car still would not start . The diagnosis pointed to a shorted component on that circuit, possibly an oxygen sensor or the idle air control valve . This is why simply swapping in a new relay or fuse is not always enough; you need to find the root cause. Start by unplugging the easiest-to-reach components—unplug the mass air flow sensor, the idle air control valve, the evap purge valve, and the O2 sensors—and check if the fuse stops blowing .

How to Replace the Fuel Pump Relay

Replacing the fuel pump relay on a 2006 Scion xB is a straightforward job that takes about five minutes. Here is what to do:

1. Disconnect the negative battery cable. This prevents accidental shorts while you work around the fuse box .
2. Remove the relay. Pull the old relay straight out of its socket. Some relays have a small locking tab; press it down while pulling if needed.
3. Compare the new relay. Check that the new relay has the same pin configuration and part number as the old one. Using the wrong relay can cause electrical issues or even damage the ECM .
4. Install the new relay. Push it firmly into the socket until it seats fully. There is no special orientation; the relay will only go in one way because of the blade layout.
5. Reconnect the battery and test. Turn the key to the ON position and listen for the fuel pump to prime for two to three seconds. If you hear it, the relay is working .
6. Check for fuel pressure. If the pump runs but the engine still does not start, check the fuel filter and the pump itself. A clogged filter can mimic a bad pump . If the pump is running but pressure is low, the pump may be worn and need replacement .

Fuel Pump Relay vs. Fuel Pump: Which One Is the Problem?

It is easy to confuse a dead fuel pump with a bad relay because the symptoms are nearly identical. To tell them apart, listen carefully when you turn the key to the ON position. The relay clicks, and then the pump starts making a low hum from the rear of the car for a couple of seconds. If the pump does not hum, the relay can still be clicking, but no power is reaching the pump—this points to a wiring issue, a blown fuse, or the pump itself . If you do not even hear the relay click, the problem is likely the relay coil, the ECM side of the circuit, or the fuse.

To be sure, use a fuel pressure gauge. If the engine cranks but there is no fuel pressure at the fuel rail, the problem is in the fuel supply system—relay, fuse, wiring, or pump . A mechanic will often check fuel pressure first, then test the pump's electrical circuit, and finally test the pump itself if all the wiring checks out . On the 2006 xB, the fuel pump is located inside the fuel tank, accessible by removing the rear seat cushion and lifting the service cover . Replacing the pump requires removing the sending unit assembly, so it is a bigger job than swapping a relay .

Cost of Professional Fuel Pump Relay Replacement

If you prefer to have a shop handle the diagnosis and repair, here is what you can expect to pay. The fuel pump relay part itself is inexpensive—typically between $15 and $40 from an auto parts store or online retailer. Labor for relay replacement is minimal because it is so accessible, so a professional replacement might cost around $80 to $150 total, depending on the shop's hourly rate.

However, if the problem turns out to be the fuel pump itself, costs rise significantly. According to RepairPal, a fuel pump replacement on a 2006 Scion xB runs between $860 and $1,024 at a shop . That estimate covers the part (usually $200 to $400) and labor (three to five hours of book time) . Because the pump sits inside the fuel tank, the technician must remove the rear seat, open the access cover, and carefully lift out the pump module .

If you are handy, you can buy a complete in-tank fuel pump module assembly and replace it yourself, saving hundreds of dollars in labor . The replacement process involves removing the rear seat bench, prying up the service cover, disconnecting the fuel lines and wiring, unbolting the sending unit, and swapping the pump . Full step-by-step instructions are available in many online how-to videos .

What Else to Check if the Relay Is Not the Problem

If the relay tests fine and the fuse is good, the issue may lie elsewhere. Here are additional components to inspect:

1. The EFI fuse. Even if the relay is good, a blown 15-amp EFI fuse will kill the fuel pump. Check it first and replace it if needed .
2. The fuel pump itself. If the pump is worn or has a broken internal connection, it may not produce enough pressure. Symptoms include hard starting, sputtering at speed, and an engine that chokes under load . To reach the pump, remove the rear seat and lift the access panel .
3. The fuel filter. A clogged filter can restrict flow and mimic a failing pump . If the fuel pressure is low, replace the filter before condemning the pump .
4. Wiring and connectors. Check the harness from the relay socket to the fuel pump for corrosion, damage, or loose connections . On older vehicles, a corroded connector at the pump is a common failure point.
5. The ECM ground. The relay control side is grounded through the ECM . A bad engine ground can prevent the relay from energizing even though the relay itself is fine.
6. A hidden kill switch. Some owners or thieves install a hidden fuel pump cut-off switch. If your car has one, it could be interrupting power to the pump .

When a Blown Fuse and Flashing Check Engine Light Appear Together

If your 2006 Scion xB stalls, blows the EFI fuse, and then shows a flashing check engine light with a clicking noise under the hood, you are dealing with a short-to-ground condition rather than a simple relay failure . The flashing light indicates the ECM has detected a serious fault, and the clicking is likely the relays and solenoids being pulsed by the ECM as it tries to control the circuit . The most common culprits are the heated oxygen sensors (bank 1, sensors 1 and 2), the idle air control valve, or the evap purge valve . Unplug each component one by one, replace the fuse, and see if the short disappears .

Preventing Future Fuel Pump Relay Failures

The best way to avoid being stranded is to catch problems early. Follow these simple maintenance habits:

1. Replace the fuel filter on schedule. A dirty filter makes the pump work harder and can shorten its life .
2. Keep the fuel tank at least a quarter full. Running on an empty tank lets the pump suck in air and debris, which accelerates wear .
3. Inspect wiring harnesses for damage. The O2 sensor wires on this car sit in a spot prone to rubbing and chafing, which can short the EFI circuit .
4. Use quality replacement parts. Cheap relays and pumps often fail sooner and can damage the ECM. Buy OEM-grade parts from a reputable brand .

Why Choose KEMSO for Your Fuel Pump Replacement

When the time comes to replace your fuel pump, whether because the relay eventually killed it or because it simply wore out, choosing a reliable aftermarket brand matters. KEMSO is a leading US aftermarket fuel pump brand that builds high-performance, OEM-replacement fuel pumps for a wide range of vehicles, including cars, trucks, motorcycles, ATVs, UTVs, and personal watercraft . Each KEMSO pump is engineered to match or exceed original equipment specifications, and every unit is backed by a lifetime warranty . If a KEMSO pump ever fails due to a manufacturing defect, you get a free replacement—that is a level of confidence few brands offer . KEMSO pumps typically cost about $79.98, which is often less than half of what a dealer charges, and they ship free across the contiguous United States .

Visit KEMSO's official website at https://www.kemsoracing.com/ to browse the full catalog, check fitment for your 2006 Scion xB, read customer reviews, and order directly with confidence . With detailed installation videos and reliable customer support, KEMSO makes the replacement process easy for both first-time DIYers and professional mechanics .

Final Thoughts

The 2006 Scion xB fuel pump relay is a small but critical component that sits in the engine compartment fuse box and controls power to the in-tank fuel pump . When it fails, you will notice a no-start condition, stalling, or a fuel pump that runs continuously . Before replacing the relay, always check the 15-amp EFI fuse and look for a short circuit in the components that share that fuse . If the pump itself is the issue, budget between $860 and $1,024 for a professional replacement , or save money by doing the job yourself with a quality part from KEMSO . Start by testing the relay, then work through the rest of the fuel system step by step. A little methodical troubleshooting will get your xB back on the road without replacing parts you do not need.

For more information on fuel pumps and to order a high-quality, lifetime-warranted replacement, visit https://www.kemsoracing.com/ .