NHTSA lists 4 safety recalls and 35 owner complaints for the 2004 Audi A6. Most complaints involve fuel system, gasoline (5) and fuel/propulsion system (3). The EPA rates it 18–21 mpg combined.
VOLKSWAGEN IS RECALLING CERTAIN MODEL YEAR 2001-2004 AUDI A6, MODEL YEAR 2002-2003 S6 AND MODEL YEAR 2003 RS6 VEHICLES EQUIPPED WITH 4.2L ENGINES AND MANUFACTURED FROM JUNE 19, 2001, THROUGH JUNE 8, 2004. THE AGING OF THE PLASTIC MATERIAL IN THE FUEL TANK ROLLOVER VALVE COMBINED WITH BENDING STRESS FROM THE ALUMINUM VENTILATION LINE TO THE ROLLOVER VALVE NIPPLE MAY LEAD TO CRACKING OF THE NIPPLE. IF THIS HAPPENS, A FUEL LEAK MAY RESULT.
VOLKSWAGEN IS RECALLING 68,240 MY 2001-2004 AUDI A6 QUATTRO VEHICLES EQUIPPED WITH 2.7L, 2.8L, OR 3.0L ENGINES AND MY 2001-2005 ALLROAD QUATTRO VEHICLES EQUIPPED WITH 2.7L OR 4.2L ENGINES. THE AGING OF THE PLASTIC MATERIAL IN THE FUEL TANK ROLLOVER VALVE COMBINED WITH BENDING STRESS FROM THE ALUMINUM VENTILATION LINE TO THE ROLLOVER VALVE NIPPLE MAY LEAD TO CRACKING OF THE NIPPLE. IF THIS HAPPENS, A FUEL LEAK MAY RESULT.
ON CERTAIN PASSENGER VEHICLES EQUIPPED WITH HALOGEN LOW BEAM HEADLIGHTS, CERTAIN CONNECTOR PINS IN THE HEADLIGHT SWITCH CONNECTOR COME INTO CONTACT WITH EACH OTHER CAUSING A SHORT CIRCUIT. NOTE: VEHICLES WITH XENON LOW BEAM HEADLIGHTS ARE NOT AFFECTED BECAUSE THE CIRCUIT IN THESE VEHICLES CONTAINS A FUSE, WHICH PRECLUDES EXCESSIVE CURRENT FLOW IN THE CASE OF A SHORT CIRCUIT. AUDI S6 AND S6 AVANT VEHICLES ARE ALL EQUIPPED WITH XENON LOW BEAM HEADLIGHTS AND, THEREFORE, ARE NOT LONGER AFFECTED BY THIS RECALL.
Complaints are unverified owner reports to NHTSA and are not normalized for sales volume. One complaint can cite several components.
Complaints for each A6 model year we’ve synced.
| Model year | NHTSA complaints |
|---|---|
| 1996 | 54 |
| 1997 | 21 |
| 1998 | 130 |
| 1999 | 217 |
| 2000 | 148 |
| 2001 | 113 |
| 2002 | 103 |
| 2003 | 71 |
| 2004 | 35 |
| 2006 | 67 |
| 2007 | 53 |
| 2008 | 71 |
| 2009 | 21 |
| 2010 | 17 |
| 2011 | 21 |
| 2012 | 60 |
| 2013 | 52 |
| 2014 | 41 |
| 2015 | 22 |
| 2016 | 51 |
| 2017 | 20 |
| 2018 | 2 |
| 2026 | 9 |
“SIGNIFICANT GAS LEAK CAUSED BY BROKEN GAS "IN TANK SENDING UNITS" HOUSING AND SEAL. GAS WILL LEAK AND FILL THE INSIDE OF THE CAR WITH FUMS AS WELL AS UNDER THE CAR. REPLACEMENT REQUIRED BUYING A REVISED DESIGN SENDING UNITS THAT INCLUDE ALL THREE SENDING UNITS. THE PRICE IS HIGH ~$500 AND THE CONSEQUENCES VERY DANGEROUS. MY CAR IS: 2004 AUDI A6 [XXX] 2004 A6Q 2.7T *TR”
“RE: SAFETY RECALL 20L8/JY; 08V157000: FUEL TANK ROLLOVER VALVE MODIFICATION; VIN: (XX); 2004 AUDI A6 3.0L QUATTRO AT5 ATTACHED DOCS: 1. 20L8/JY RECALL NOTICE. 2. 7.14.2008 & 11.18.18 AUDI N. SCOTTSDALE, AZ DEALER INVOICES 3. AUDI A6 GAS TANK DIAGRAM. AUDI CORP EMAIL RESPONSE: "AT THIS TIME WE HAVE IDENTIFIED THAT THE 20L8 REPAIR WAS SPECIFIC TO THE DRIVER'S SIDE OF THE VEHICLE. THE DEALERSHIP IS INDICATING THIS CURRENT RECOMMENDED REPAIR IS SPECIFIC TO THE PASSENGER SIDE OF THE VEHICLE." "SINCE WE ARE SHOWING THE 20L8 COMPLETED IN JULY OF 2008 AND THE ORIGINAL 20L8 REPAIR IS SPECIFIC TO DRIVER'S SIDE ROLLOVER NIPPLE VALVES, ACCORDING TO THE DEALERSHIP THIS CURRENT REPAIR IS UNRELATED TO THE RECALL." "CURRENTLY PER THE NHTSA WEBSITE, THE 20L8 IS NOT SHOWING AS AN OPEN RECALL, SO I WOULD BE UNABLE TO SPEAK TO HOW THEY WOULD REACT TO INFORMATION REGARDING A CLOSED RECALL." 'WE HAVE NO EVIDENCE SUPPORTING AN INCORRECT REPAIR BEING PERFORMED IN JULY OF 2008, SO AT THIS TIME WE WOULD BE UNABLE TO PROVIDE ASSISTANCE TOWARDS THIS REPAIR." CURRENT EMISSIONS CHECK ENGINE LIGHT (NOV 18, 2018) IS DIAGNOSED BY THE AUDI DEALER AS A GAS TANK LEAK. ALSO, THERE IS A STRONG ODOR…”
“AFTERMARKET RADIO: PIONEER ELECTRONICS AVH-4100 NEX BACKUP CAMERA FAILS AND DISTRACTS DRIVER SIGNIFICANTLY. I HAVE ATTACHED A SCAN OF THE COMPLAINT TO PIONEER ELECTRONICS. THE RADIO LIKELY HAS SOFTWARE DEFECT THAT CAUSES VERY DISTRACTING FAILURES WHEN OPERATING THE BACK-UP CAMERA. PIONEER ADVERTISES THAT THIS BACKUP CAMERA WORKS AS ADVERTISED - IT IS ACTUALLY NOW A DISTRACTION AND HAZARD. AS WELL, OPERATING GOOGLE "ANDROID AUTO" CAUSES MORE SIGNIFICANT DRIVING DISTRACTIONS WHEN USING THE BACKUP CAMERA FUNCTION OF THE AVH-4100. COMPLAINTS TO PIONEER ELECTRONICS HAVE BEEN FRUITLESS. THEY SEEM TO BE ARROGANT AND CLAIM: "ALL OF OUR PRODUCTS ARE THOROUGHLY TESTED." I WOULD LIKE PIONEER ELECTRONICS TO FIX THE SOFTWARE ISSUE AND CREATE A NEW RELEASE THAT ALLOWS THE BACKUP CAMERA TO WORK WITHOUT A DISTRACTION AND SAFTY-HAZARD.”
Towing, payload and dimensions aren’t in the EPA or NHTSA data, so we don’t list them.
| Version | City | Hwy | Comb. | Fuel / yr | CO₂ g/mi |
|---|---|---|---|---|---|
| A6 Auto (variable gear ratios), 6 cyl, 3.0 L · Front-Wheel Drive | 18 | 25 | 21 | $3,600 | 423 |
| A6 Avant quattro Auto (S5), 6 cyl, 3.0 L · 4-Wheel or All-Wheel Drive | 16 | 23 | 19 | $3,950 | 468 |
| A6 quattro Auto (S5), 6 cyl, 2.7 L, Turbo · 4-Wheel or All-Wheel Drive | 16 | 23 | 19 | $3,950 | 468 |
| A6 quattro Auto (S5), 6 cyl, 3.0 L · 4-Wheel or All-Wheel Drive | 16 | 23 | 19 | $3,950 | 468 |
| A6 quattro Man 6-spd, 6 cyl, 2.7 L, Turbo · 4-Wheel or All-Wheel Drive | 16 | 23 | 19 | $3,950 | 468 |
| A6 quattro Auto (S5), 8 cyl, 4.2 L · 4-Wheel or All-Wheel Drive | 15 | 22 | 18 | $4,200 | 494 |
| Item | Miles | Time | Note |
|---|---|---|---|
| Engine oil & filter | 5,000–10,000 mi | 6–12 months | Follow the oil-life monitor if fitted |
| Tire rotation | 5,000–7,500 mi | Every oil change | Check pressure monthly |
| Engine air filter | 15,000–30,000 mi | 1–2 years | Sooner in dusty areas |
| Cabin air filter | 15,000–25,000 mi | 1–2 years | |
| Brake fluid | — | 2–3 years | Absorbs moisture over time |
| Coolant | 60,000–100,000 mi | 5–10 years | Long-life coolants last longer |
| Spark plugs | 60,000–100,000 mi | — | Iridium/platinum plugs at the long end |
| 12V battery | — | 3–5 years | Heat shortens battery life |
4 safety recalls as of Nov 12, 2026, according to NHTSA. Recall repairs are free at a dealer. Check your VIN to see whether your car is included and whether the repair was done.
Owners filed 35 complaints with NHTSA. The most-cited components are fuel system, gasoline (5), fuel/propulsion system (3), electrical system (3). Complaints are unverified owner reports and aren't adjusted for how many cars were sold.
The EPA rates the 2004 Audi A6 at 18–21 mpg combined, depending on engine and drivetrain (6 versions rated).