2006-2009 Lexus RX330 & RX350 Engine Fuse Box: A Guide to Failures, Part Numbers, and Replacement

Symptoms of a Failing Fuse Box

A failing engine fuse box in a 2006 Lexus RX330 or 2007-2009 Lexus RX350 can cause a wide range of confusing symptoms. Because it controls so many different systems, problems can appear unrelated at first. Failures often stem from internal corrosion, blown main fuses, or faulty integrated relays.

• No-Start Condition: The vehicle may crank but fail to start. This can happen if the main 30-amp 'AM2' fuse blows, 🎬 Watch how a blown AM2 fuse causes a no-start condition. cutting power to the ignition system and preventing the engine computer (ECU) from receiving the 'on' signal. A faulty fuel pump relay within the box can also prevent the engine from getting fuel.
• Multiple Unrelated Electrical Failures: You might experience several systems failing at once. For example, the power windows, radio, and interior lights may stop working simultaneously. This often points to a main fusible link or a shared power circuit within the fuse box 🎬 Learn how to diagnose and replace a main fusible link. being compromised.
• Specific Components Not Working: A single, high-power component like the headlights, cooling fan, or air conditioning blower may stop functioning. While this could be a simple fuse, it can also indicate a failure of the specific relay for that component inside the main fuse box assembly.
• Intermittent Electrical Gremlins: Lights flickering, the radio cutting out, or warning lights flashing randomly can be a sign of a poor connection or corrosion within the fuse box. Some owners have reported strange electrical behavior after heavy rain, which could point to water intrusion.
• Visible Corrosion or Melting: A visual inspection under the fuse box cover may reveal white or greenish corrosion on the terminals, or signs of plastic melting around a specific fuse or relay socket, indicating a severe overload or short circuit.
• OBD-II Port Inoperative: If your code scanner won't power on when plugged into the diagnostic port, it's often because the fuse that powers the port has blown. This fuse is frequently shared with the cigarette lighter/power outlet, so check if that is also dead.

OBD-II Codes Associated with Fuse Box Failure

A failing fuse box rarely triggers a code that points directly to the box itself. Instead, you are more likely to see a variety of codes related to the systems that have lost power or communication. Common codes include:

• Communication Codes (U-prefix): Codes like U0100 (Lost Communication with ECM/PCM), U0121 (Lost Communication with ABS Control Module), or U0140 (Lost Communication with Body Control Module) can be set if the fuse box fails to supply power to these essential modules.
• Component Circuit Codes: You may see codes for specific circuits that are routed through the fuse box, such as fuel pump circuit errors or oxygen sensor heater circuit malfunctions.

Known Issues and Recalls

As of early 2026, there are no specific recalls or Technical Service Bulletins (TSBs) from Lexus or the NHTSA that target the engine bay fuse box for the 2006 RX330 or 2007-2009 RX350. The primary known issues are related to general electrical failures from blown fuses or potential water damage, as discussed in the symptoms section.

Variant & Compatibility Warnings

Important: Models WITHOUT Sport Package Only

This engine bay fuse box fits the 2006 Lexus RX330 and 2007-2008 Lexus RX350 models that were sold WITHOUT the optional Sport Package. The Sport Package often included a sport-tuned air suspension, which requires different relays and fuse configurations not present in the standard fuse box. For the 2009 Lexus RX350, this distinction appears to have been eliminated, with most used parts listings indicating it fits all models for that year.

How to check your vehicle:

• Look for a switch or button for the air suspension, which often includes settings for height control ('HI', 'N', 'LO').
• Check your vehicle's original window sticker or specifications if available.
• When in doubt, the most reliable method is to visually compare your existing fuse box layout and part number with the replacement unit before purchasing.

Buying a Used Fuse Box: What to Look For

A used OEM fuse box is often a reliable and cost-effective solution for these vehicles. Since these units do not require programming, a direct swap is feasible. Here’s what to inspect:

• Verify Part Numbers: The main assembly is typically part number 82620-48040. The cover and other housing components may have separate numbers like 82672-48040. Ensure the primary number matches.
• Check for Corrosion: Carefully inspect all terminals, pins, and sockets, both on top and where the main harnesses connect underneath. Avoid any unit with signs of white, green, or blue powder, which indicates corrosion from moisture.
• Look for Heat Damage: Check for any melted plastic, discoloration, or warped areas around the fuse and relay sockets. This is a major red flag indicating a past major short circuit that could have damaged the internal wiring of the block.
• Inspect for Physical Damage: Ensure the plastic housing is not cracked and that all mounting tabs are intact. A broken housing can allow moisture and dirt to enter, leading to future failures.
• Get the Cover: Make sure the sale includes the main fuse box cover. A missing or damaged cover is the number one cause of future water and debris contamination.

Replacement Overview

Replacing the engine bay fuse box is a straightforward job that is feasible for a DIY mechanic with basic tools. The unit is located in the engine compartment, typically on the driver's side.

1. Disconnect the Battery: Always disconnect the negative battery terminal before working on any major electrical component.
2. Remove the Cover: Release the clips holding the top cover onto the fuse box.
3. Disconnect Harnesses: Carefully unplug the large electrical connectors that plug into the bottom and sides of the fuse box. They have locking tabs that must be depressed.
4. Unbolt the Fuse Box: Remove the bolts that secure the fuse box assembly to the vehicle's chassis.
5. Transfer Fuses and Relays: Your replacement fuse box may not come with all fuses and relays. Carefully transfer them from your old box to the new one, matching their positions exactly. Taking a photo beforehand is highly recommended.
6. Installation: Installation is the reverse of removal. Ensure all connectors click securely into place and that the battery is reconnected last.

Cost of Replacement

Costs can vary based on your location and choice of parts. All prices are estimates.

Frequently Asked Questions (FAQ)