2021 Audi A6 Complaints

UNKNOWN OR OTHER — Filed 04/01/2026

My 2021 Audi A6 produces a strong mold and mildew odor from the HVAC/air conditioning system. The smell occurs consistently after the air conditioning is turned off and persists when entering the vehicle. The issue appears to originate from mold growth on the evaporator coil or dampers, likely caused by moisture accumulation and inadequate condensate drainage in the HVAC system. The vehicle was inspected and treated at an authorized Audi dealership; however, the treatment did not resolve the issue and the odor returned. Online owner forums and communities document the same problem across multiple Audi models and model years, suggesting this is a systemic design or manufacturing issue rather than an isolated incident. A passenger in the vehicle — a minor child with a documented mold allergy — has experienced allergic reactions as a result of exposure to the vehicle's air conditioning output. This constitutes a health and safety concern. The mold contamination in the HVAC system poses a risk to vehicle occupants, particularly those with respiratory conditions or mold sensitivities. I am requesting that NHTSA investigate whether a defect exists in the HVAC/evaporator system design across Audi vehicles, and whether a safety recall or technical service bulletin is warranted.

ENGINE AND ENGINE COOLING — Filed 03/10/2026

The contact owns a 2021 Audi A6. The contact stated while driving at an undisclosed speed, the vehicle overheated. The engine overheating and the low coolant warning light illuminated. In addition, the engine seized. The vehicle was taken to the dealer where it was diagnosed with a coolant leak and a failed coolant pump vacuum. The contact was informed that the coolant pump vacuum assembly needed to be replaced. The vehicle was not repaired. In addition, the contact was informed that the failure was a known failure of the vehicle. The manufacturer was made aware of the failure and a case was filed. The contact was advised to contact the NHTSA Hotline and report the failure. The failure mileage was approximately 80,000.

ENGINE — Filed 05/05/2026

Thermostat housing and oil cooler bracket leaking coolant with only 56k miles on the car

POWER TRAIN — Filed 04/04/2026

I was driving my vehicle when the engine surged and then a transmission warning light came on and there was an immediate and complete loss of drive power. After the vehicle glided to a stop, there was no drive transmission in either forward or reverse. There was no pre-warning and no earlier incidence that led up to this issue. The vehicle is five years old with 39,834 miles and has had all routine maintenance and mileage interval services performed at the dealership, including its recent (Dec-25) 40,000-mile service. Thankfully this complete failure occurred when I was in my neighborhood and travelling 20mph; otherwise, the results could have been catastrophic had it occurred on a multilane highway at speeds of 65-70 MPH. The vehicle was towed to Audi of Indianapolis where the issue was identified as one broken bolt and two loose bolts for the transmission filter cap. This matches a known Audi Issue with a Technical Service Bulletin issued December 13, 2024, where they acknowledge a complete loss of power and a root cause of broken/loose bolts in the transmission filter. This is a known issue and is happening on low mileage well serviced vehicles. Because this issue is known and could result in a severe accident and/or loss of life under high-speed multi-lane highway conditions, it seems Audi of America should issue a recall versus just a TSB and/or extend the warranty for this issue up to 10 years or 100,000 miles which would, perhaps, be considered a normal lifespan for a part.

POWER TRAIN,ELECTRICAL SYSTEM — Filed 02/18/2025

My alternator was not working and it was a recall and I paid to fix it and they don’t wanna pay me back. I got a new part from audi and fix it at the shop and they don’t wanna pay anything just called and she said we don’t pay only if he’s done at the dealer. And I don’t believe that! Bc dealer told me they pay if I fix it any where to get done quick bc was out stock

ELECTRICAL SYSTEM — Filed 12/07/2025

While driving at normal speed, the entire digital instrument panel suddenly went black and a red warning triangle appeared. I lost all gauges, including speedometer, fuel level, and warning indicators. This created a serious safety risk because I was in active traffic and had no way to know my speed or see alerts. My VIN shows an open recall for this exact defect (instrument cluster blackout), but the failure has already happened during normal driving. I consider the vehicle unsafe to drive until repaired.

FORWARD COLLISION AVOIDANCE — Filed 08/12/2025

The Audi Pre-sense is activated by weather. I was driving during a thunderstorm and Audi Presence activated causing the car to come to a hard stop due to precipitation. It happened again backing out of my driveway the Audi Pre-sense was activated and the car came to a hard stop. I thought I had back into another vehicle. This is very dangerous.

ELECTRICAL SYSTEM,UNKNOWN OR OTHER,FORWARD COLLISION AVOIDANCE — Filed 01/01/2024

The car has had multiple issues with warning lights and malfunctioning systems. Including : 1.Child locks 2.Every single component of the ADAS 3. Emergency services being activated at least a few times a month - this is an SOS for emergency 911 service. The repeated, continuous and mostly false warning lights are a driving distraction that can easily cause an accident. I have photos of all warning lights coming on in the vehicle. The dealership has repeated stated that they couldn't reproduce the problem even though pictures were provided and the car is still under the original warranty period. The latest attempt to fix the vehicle was to replace the sensors on the front of the vehicle. This solution was only attempted after the 4th report of the problem to the dealership where the car was serviced under the original manufacturers warranty

ELECTRICAL SYSTEM — Filed 06/23/2024

Vehicle had electrical system malfunction. Vehicle provided an electrical system malfunction and vehicle starting system malfunction warning message a few days prior to the incident. Vehicle has approximately 20.5K miles on odometer. Before I was able to bring it to service, the electrical system malfunction message became more severe and turned from yellow to red. While driving, the vehicle progressively shut down ABS, lane departure, and other systems and gave a transmission warning message. Eventually, the car lost power and I was left stranded at the side of the road.

STEERING,ELECTRICAL SYSTEM,ENGINE — Filed 09/08/2023

Car reported an engine restarter issue (with battery symbol) and recommended to contact the dealer. Car next shut down automatic restart system, and air conditioning stopped working. Within a short period of time (same day), the car listed a red battery symbol and advised to stop the car. After doing so and contacting the Audi roadside, the car was listing a series of issues on multiple symptoms while also saying in the warning message "still okay to drive". These systems included steering, braking, and what seemed to be other sensors the car powers. Finally (and within 5 minutes of the previous message of being okay to drive), the warnings were continuous and started including the transmission. The car stopped accelerating (we were on the expressway) and we thankfully got to the side of the road. This was an enormously dangerous situation as the car became fully disabled and we were subject to limited options of relief from a major traffic area. Within 30 minutes of being disabled, no electrical charge was present in the car, including emergency flashers, making the situation more dangerous as it was nighttime, so we had to abandon the car and walk down the expressway to find a hotel. Could not even put the car in neutral for the tow. Service is initially reporting a failure of the restart generator. This appears to be an alarmingly common issue with Audis.