2021 Audi Q8 Distance to Empty Display Inconsistencies

Audi Technical Service Bulletin (TSB) 17 20 06 2028440/5, issued on July 8, 2020, addresses customer concerns regarding the 'distance to empty' fuel range display in the on-board computer of various Audi models from 2005 to 2021. This bulletin, which supersedes TSB 19-98 dated August 30, 2019, clarifies the expected behavior of the fuel range indicator rather than identifying a fault requiring repair. Owners of a 2021 Audi Q8, along with many other Audi models, may experience these conditions.

Symptoms of Inconsistent Range Display

Owners of affected Audi vehicles, including the 2021 Audi Q8, may observe one or more of the following issues with their 'distance to empty' display:

• When the vehicle is completely refueled, the displayed vehicle range ("distance to empty") is different from the range shown after the previous complete refueling.
• The displayed vehicle range drops inconsistently.
• After refueling, the displayed vehicle range does not change for a long period of time.
• When driving on hilly roads for an extended period, the displayed vehicle range suddenly changes by a significant amount.
• The instrument cluster displays a fuel range of zero miles before the fuel tank is completely empty.
• Upon refueling at a displayed fuel range of zero miles, the fuel tank accepts fewer gallons than what is listed in the owner's manual capacity chart.

Important Information for Owners

Audi TSB 17 20 06 2028440/5 provides several key clarifications for owners:

• This condition does not involve or affect the accuracy of the fuel level indicator. The actual fuel level in the tank remains accurate; only the estimated 'distance to empty' display is subject to these variations.
• The range display after fill-up depends on the driving style immediately preceding the fill-up. Therefore, the range displayed after fill-up will not always be the same.
• The displayed vehicle range does not refer to the whole tank volume. Instead, it indicates a trend based on short-term to medium-term fuel consumption.
• To ensure mobility, a small amount of fuel is still available even when a fuel range of zero miles is initially displayed.
• The fuel range is calculated based on the most recent driving style, meaning the actual amount of fuel remaining may vary when a fuel range of zero is first shown.

Technical Background on Range Calculation

The primary purpose of the vehicle range display is to help prevent running out of fuel. Audi explains that the 'distance to empty' is not calculated using the average and instant consumption figures shown on the on-board computer. Instead, it uses an internal weighted value and two different calculation methods (filter algorithms).

For vehicles older than model year 2009, the calculation includes consumption figures from the last 31 miles (50 kilometers), with the most recent mileage having the highest weight. This means efficient driving before refueling can result in a higher displayed range, while aggressive driving can lead to a lower one.

For vehicles from model year 2009 and newer, a gradual driving profile is built from both the last 31 miles (50 kilometers) and the last 310 miles (500 kilometers). Short-term and long-term consumption figures are included, along with the tank volume. This method allows the range display to rise only when the vehicle is driven efficiently for extended periods, providing a more accurate vehicle range.

Fault Codes / DTCs

Audi's workshop findings confirm that there are no Diagnostic Trouble Codes (DTCs) related to fuel senders stored in the instrument cluster control module, J285 (address word 0017), associated with these range display inconsistencies. This indicates that the observed behavior is not due to an electrical or sensor malfunction but rather the inherent design of the range calculation system.

What Owners Should Know

This TSB 17 20 06 2028440/5 is informational and does not involve a repair procedure. It clarifies the normal operating characteristics of the 'distance to empty' display. There is no impact on the accuracy of the actual fuel level. If you have concerns about your Audi Q8 distance to empty display or other related issues, discussing the technical background with your authorized Audi dealer can provide further reassurance.

Source: NHTSA ID: 10177300