2011-2013 Audi A8 & S8 Fuel Tank: Decoding Fuel Smells, Recalls, and Gauge Errors

Known Issues, Recalls, and Technical Service Bulletins (TSBs)

Before assuming your fuel tank is faulty, it's crucial to be aware of several official recalls and service bulletins for the 2011-2013 Audi A8 and 2013 Audi S8. Many common symptoms, especially fuel smells, are often caused by related components, not the tank itself.

Fuel System Recalls

There are several overlapping recalls related to fuel leaks. Always check your vehicle's VIN on the NHTSA website to see which recalls apply to your specific car.

• NHTSA Recall 20AV: This recall affects some 2013-2015 A8 and S8 models. The fuel supply line for the high-pressure fuel pump can become porous over time, leading to a fuel leak and a significant fire risk. The dealer remedy is to replace the affected fuel line.
• Fuel Pressure Damper Recall: As reported by CNET and detailed in NHTSA documents, certain 2013-2016 A8 and S8 models were recalled because a supply line could become porous. The fix involves the dealer installing a fuel pressure damper in the low-pressure fuel supply, which is located inside the fuel tank. This is done to ensure the durability of the fuel line.
• NHTSA Recall 24AP: This recall applies to some 2011-2013 models with the 3.0L TFSI engine. Leaks can develop in the fuel injection system, specifically the fuel rails and injector seals, due to vibration. This is another common source of a fuel smell that is not related to the tank itself.

Fuel Gauge and Sensor TSBs

If your fuel gauge is acting up, it is more likely a sensor or software issue than a problem with the tank shell.

• TSB 2052368: This document addresses a specific issue where the fuel gauge only shows 5/8 full after a fill-up, or is slow to respond. The problem is a delayed response from fuel level sensor 3 (G237). The fix involves replacing the sensor with an updated part.
• Forum Reports: Owners on forums like AudiWorld have reported sudden fuel gauge malfunctions, often showing empty with a dash warning. In some cases, this was resolved by replacing a fuel level sender unit located under the rear seat. In other instances, a simple fuse reset has temporarily solved the problem.

Symptoms of a Failing Fuel Tank

While many symptoms point to the recalls above, the fuel tank itself can fail, though it is less common. Here are the primary symptoms.

1. Strong Fuel Odor

A persistent smell of gasoline around the vehicle is the most urgent symptom. While this is often caused by the recalled fuel lines, a crack in the plastic tank shell or a failed seal at the fuel pump or sensor access ports will also cause a strong odor and potential fire hazard.

2. Visible Fuel Leaks

Puddles or wet spots under the rear of the car are a clear sign of a leak. The tank itself is made of durable plastic, but it can be punctured by road debris or crack due to age or stress. If you see liquid fuel, stop driving the vehicle immediately.

3. Erratic Fuel Gauge or 'Fuel System Malfunction' Warning

As noted in the TSBs, this is typically a failure of the fuel level sending units located inside the tank, not the tank itself. The D4 A8/S8 uses a complex saddle tank with multiple sensors. When one fails, the system can no longer calculate the fuel level correctly, often resulting in a gauge that reads empty and a 'range 0' warning.

4. Check Engine Light with EVAP Codes

The Check Engine Light may illuminate with codes related to the EVAP system, such as P0456 (very small leak), P0442 (small leak), or others related to tank pressure. These codes indicate that fuel vapors are escaping. While a bad gas cap is a common cause, a crack in the tank or a bad seal at the fuel pump opening can also be the source of the leak.

Buying a Used Fuel Tank: What to Check

Given that a new OEM fuel tank costs over $2,000, a used OEM tank is a practical alternative for many owners. Since no major aftermarket manufacturers produce a replacement for this part, a high-quality used tank is often the best value. Here’s what to inspect carefully:

• Check for Cracks: Meticulously inspect the entire surface of the plastic tank, especially around seams and mounting points. Pay close attention to the top of the tank where the fuel pump and sending units mount, as stress cracks can develop there.
• Inspect All Nipples and Connectors: The tank has multiple plastic nipples for fuel and vapor lines. Ensure every single one is perfectly intact, with no cracks, chips, or stress marks. A broken nipple will render the entire tank useless.
• Verify Part Number: Confirm the part number on the tank is 4H0201060M. This part is known to supersede 4H0201060J.
• Examine the Interior: If possible, look inside the tank with a flashlight. It should be clean and free of debris or any signs of contamination.
• Confirm Connector Shapes: As a general precaution, compare the electrical connector ports on the used tank to your original. While they should be standard for this part number, it's a wise final check.

Replacement Difficulty and Cost

Installation Details

• Difficulty: 5 out of 5 (Professional Recommended)
• DIY Feasibility: Not Recommended

Replacing the fuel tank on a D4 platform A8 or S8 is a very complex and labor-intensive job. It is not considered a DIY task for the average home mechanic. The procedure requires dropping the rear subframe and exhaust system to gain access, which necessitates specialized tools, a vehicle lift, and significant expertise. One owner reported being quoted $3,500 in labor alone for the job.

Cost Comparison

The high cost of a new tank and the intensive labor make this a very expensive repair. This is why a good used OEM tank can provide significant savings.

Frequently Asked Questions (FAQ)