2005-2010 Scion tC Fuel Tank: Diagnosing EVAP Leaks and Replacement Guide
This guide covers common failure symptoms like check engine lights, replacement costs, and what to inspect when buying a used fuel tank for your first-generation Scion tC.
- A Check Engine Light with codes P0455 or P0442 is the most common symptom, often caused by a leak in the tank or a loose gas cap.
- A visible fuel leak or strong gasoline smell is a critical fire hazard; the vehicle should not be driven.
- When buying a used tank, prioritize a rust-free unit from a dry climate and inspect it for dents and internal debris.
- Replacement is a difficult (4/5) DIY job due to the safety risks of handling gasoline; professional installation is recommended for most owners.
Symptoms of a Failing Fuel Tank
A problem with the fuel tank on a 2005-2010 Scion tC can manifest in several ways, ranging from a simple warning light to a dangerous fuel leak.
Check Engine Light for EVAP Leaks (Codes P0455, P0442)
The most common symptom is an illuminated Check Engine Light (CEL). The first-generation tC's fuel tank is a sealed, pressurized system. If the onboard computer detects a leak, it will store a diagnostic trouble code. Common codes include:
- P0455 (Evaporative Emission System Leak Detected - Large Leak): This often points to a significant leak. While it can be caused by something as simple as a loose or faulty gas cap, it can also indicate a cracked fuel tank, a damaged filler neck, or a disconnected EVAP hose.
- P0442 (Evaporative Emission System Leak Detected - Small Leak): This code points to a much smaller leak, such as a pinhole from rust or a failing seal. These small leaks can be harder to diagnose and may originate from the tank itself or other components in the EVAP system.
Fuel Smell
A strong smell of raw gasoline around the rear of the vehicle, especially after filling up, is a clear sign of a fuel leak. The leak could be from a crack in the tank, a rusted seam, or a bad seal where the fuel pump assembly mounts to the top of the tank. Do not ignore this symptom, as it indicates a serious fire hazard.
Visible Fuel Leaks or Puddles
Seeing gasoline dripping or puddled under the rear of the car is a critical safety issue. The 2005-2010 Scion tC uses a steel tank, which can rust over time, especially in regions that use road salt in the winter. Leaks often develop along the seams or where the support straps hold the tank against the vehicle's body. One owner reported significant leaks during fill-ups, which pointed to a crack or seal failure near the top of the tank.
Inaccurate or Stuck Fuel Gauge
If your fuel gauge is behaving erratically or is stuck on full or empty, it could be related to the tank. A dent in the bottom of the fuel tank can interfere with the movement of the fuel level sender's float arm, causing it to give false readings. While the sender unit itself is the more common culprit, physical damage to the tank should not be ruled out.
Warning: A fuel leak is a severe fire hazard. If you smell or see gasoline leaking from your vehicle, do not drive it. Have it towed to a repair facility immediately.
Known Issues, Recalls, and TSBs
As of this writing, there are no active recalls or Technical Service Bulletins (TSBs) from Toyota or the NHTSA specifically for fuel tank failure on the 2005-2010 Scion tC. The primary cause of failure is age-related corrosion (rust) on the steel tank or physical damage from road debris.
Buying a Used 2005-2010 Scion tC Fuel Tank
A recycled OEM fuel tank from a low-mileage, dry-climate vehicle can be an excellent, cost-effective alternative to an expensive new unit. However, careful inspection is crucial before you buy.
Inspection Checklist for a Used Tank:
- Check for Rust: This is the most important check. Thoroughly inspect the entire surface, paying close attention to the seams where the top and bottom halves of the tank are welded together. Also, check the areas where the two metal support straps make contact, as moisture can get trapped there and cause corrosion.
- Look for Dents: Minor dents are usually cosmetic, but a large dent on the bottom of the tank can affect fuel gauge accuracy by impeding the fuel sender float. Reject any tank with significant bottom damage.
- Inspect the Inside: Shine a flashlight into the fuel pump opening. Look for any signs of internal rust, sediment, or a varnish-like coating from old fuel. A clean interior is essential to prevent clogging your new fuel pump and injectors.
- Examine Mounting Points: Check the fuel pump mounting ring for any damage or warping. Ensure the threaded studs are intact. Also, inspect the filler neck and EVAP line connections to make sure they are not cracked or bent.
- Verify Compatibility: All 2005-2010 Scion tC models use the same 14.5-gallon fuel tank. The primary OEM part number is 77001-21101, which supersedes the earlier 77001-21100. Both will fit correctly.
Pro Tip: When buying a used tank, ask about the donor vehicle. A tank from a southern or western state is far less likely to have rust issues than one from the Northeast or Midwest (the "Salt Belt").
Replacement Overview
Replacing the fuel tank is an advanced DIY job that requires specific safety precautions. If you are not comfortable working with fuel systems, this job is best left to a professional.
- Difficulty: 4 out of 5
- Estimated Time: 3-5 hours
- Safety First: The fuel system must be depressurized, and the tank must be safely drained before removal. This procedure involves a high risk of fire. Always work in a well-ventilated area, disconnect the battery, have a fire extinguisher rated for gasoline fires nearby, and avoid all sources of sparks or open flames.
High-Level Steps:
- Relieve fuel pressure by running the engine after disconnecting the fuel pump relay or fuse.
- Disconnect the negative battery terminal.
- Safely lift and support the vehicle on jack stands.
- Siphon all remaining fuel from the tank into an approved container.
- Support the fuel tank with a transmission jack or floor jack with a wide block of wood.
- Disconnect the filler neck hose and EVAP hoses.
- Loosen and remove the bolts for the two metal straps holding the tank in place.
- Carefully lower the tank a few inches to gain access to the electrical connectors and fuel lines on top.
- Disconnect the fuel pump wiring and fuel lines.
- Lower the tank completely and remove it from under the vehicle.
Installation is the reverse of removal. It is highly recommended to replace the fuel pump O-ring/seal and lock ring when installing the new tank to ensure a proper seal for the EVAP system.
Cost Comparison
Prices can vary based on location and supplier, but this provides a general estimate for the 2005-2010 Scion tC fuel tank.
| Part Type | Estimated Cost | Notes |
|---|---|---|
| New OEM | $600 - $900 | Highest quality and perfect fit, but most expensive. |
| New Aftermarket | $180 - $300 | A budget-friendly option. Quality can vary. Often includes a new lock ring and O-ring. |
| Used OEM | $100 - $400 | Great value if a clean, rust-free tank can be found. |
| Shop Labor | $350 - $500 | Typically 3-4 hours of professional labor. |
Frequently Asked Questions (FAQ)
Can I repair a leaking steel fuel tank?
While professional repair is sometimes possible, it is generally not recommended for DIYers due to the extreme danger of welding or sealing a container that has held flammable vapors. Replacement is the safest and most reliable solution.
Do I need to replace the fuel pump when I replace the tank?
It is not required, but it is strongly recommended. The labor to access the fuel pump is the same as replacing the tank. If your vehicle has high mileage, replacing the fuel pump assembly at the same time is preventative maintenance that can save you from having to do the same job again in the near future.
Will a bad fuel tank affect my car's performance?
Yes. A leak in the EVAP system can sometimes cause a rough idle or difficulty starting. More critically, if the inside of the tank is rusted, rust particles can be drawn into the fuel pump, clogging the filter and injectors, which will severely impact engine performance.
Why did my check engine light come on after getting gas?
If the check engine light (often with code P0455) appears shortly after a fill-up, the first thing to check is the gas cap. Make sure it is tightened until it clicks at least once. A loose, damaged, or incorrect gas cap is the most common cause of an EVAP system leak code.
Technical Specifications
OEM Part Numbers: 77001-21101 7700121101 77001-21100 7700121100
Capacity: 14.5 Gallons (55 Liters). Material: Steel. Fits all 2005, 2006, 2007, 2008, 2009, and 2010 Scion tC models.
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Scion tC:
- Symptoms of a Failing Fuel Tank
- Check Engine Light for EVAP Leaks (Codes P0455, P0442)
- Fuel Smell
- Visible Fuel Leaks or Puddles
- Inaccurate or Stuck Fuel Gauge
- Known Issues, Recalls, and TSBs
- Buying a Used 2005-2010 Scion tC Fuel Tank
- Inspection Checklist for a Used Tank:
- Replacement Overview
- High-Level Steps:
- Cost Comparison
- Frequently Asked Questions (FAQ)
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