🔧 RX350 - Fuel Cap Replacement

Replacing the fuel cap is a simple job: you remove the old cap and install a new one that seals correctly. A worn or incorrect cap can cause fuel odors and can turn on the Check Engine Light due to an EVAP (fuel vapor) leak.

Difficulty Level: Beginner | Estimated Time: 5-10 minutes

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⚠️ Safety & Precautions

• ⚠️ Do this with the engine OFF and away from sparks/flames.
• ⚠️ Don’t smoke while working near the fuel filler area.
• ⚠️ If the cap hisses when loosening, open it slowly to relieve pressure.
• ⚠️ Battery disconnect is not required.

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🔧 Required Tools

You'll need the following tools for this repair:

• Nitrile gloves
• Shop towel
• Flashlight

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Fuel cap (OEM-equivalent, tethered) - Qty: 1

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📋 Before You Begin

• Park your RX350 on level ground and turn the engine OFF.
• Make sure the area around the fuel door is clean (wipe with a shop towel).

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Open the fuel door

• Use your hand to open the fuel door on the left rear quarter panel.
• Use a flashlight if it’s dark so you can see the cap and sealing area.

Step 2: Remove the old fuel cap

• Wear nitrile gloves.
• Turn the cap counterclockwise until it releases.
• If you hear a hiss, pause and loosen slowly. Slow = safer and cleaner.
• Let the cap hang by its tether (the little strap that keeps it from dropping). “Tether” just means it’s attached so it won’t fall.

Step 3: Inspect and clean the sealing surfaces

• Use a shop towel to wipe the fuel filler neck sealing lip (the round surface the cap seals against).
• Check for dirt, sand, or nicks. A dirty seal can mimic a bad cap.

Step 4: Install the new fuel cap

• Thread the new cap on by hand (clockwise).
• Tighten until you hear/feel it click several times (typically 1–3 clicks). This is the built-in limiter that ensures proper tightness.
• Make sure the tether isn’t twisted and the cap sits flat.

Step 5: Close the fuel door

• Close the fuel door securely with your hand.
• Use a flashlight to confirm nothing is pinched or misaligned.

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✅ After Repair

• Start your RX350 and confirm there’s no fuel smell around the filler area.
• If you replaced the cap because of a Check Engine Light, it may take a few drive cycles for the light to turn off on its own.
• If the light stays on after a few days, the EVAP leak may be elsewhere and may need a scan for codes.

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💰 DIY vs Shop Cost

Shop Cost: $30-$90 (parts + labor)

DIY Cost: $15-$45 (parts only)

You Save: $15-$45 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 0.1-0.3 hours.

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🎯 Ready to get started?

HowToo makes it easy: same-day/2-day shipping on every part, plus all the tools and specialty tools you need! Check out the parts and tools sections below to add everything to your cart.