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2021 Audi A6 — buzzing noise only at one engine RPM

FlatSixMilesCommunity StarterJun 13, 20262021 Audi A6 PrestigeChicago
2021 Audi A6 Prestige, about 91,000 miles. There is a light buzz from the dash at one narrow RPM range. It disappears above and below that speed. Any good method for locating trim resonance without randomly adding foam everywhere?
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40 replies

FlatSixMilesCommunity StarterCommunity StarterJun 13, 2026permalink
I went back under the 2021 Audi A6 and it only happens after a heat soak, not on a cold start. I refuse to clear codes until someone else sees them.
WeekendDriver470Community StarterCommunity StarterJun 13, 2026permalink
Agree — and I'd add this: Two 2021 Audi A6s can feel identical and have different causes, so measure before you copy someone else's repair. You'll know quickly if you're on the wrong tree. On “buzzing noise only at one engine rpm,” that was the fork that mattered for me. That's the sequence I'd use. If that fails I'll eat the diagnostic fee.
DieselScout442Community StarterCommunity StarterJun 13, 2026permalink
If it were in my driveway, capture voltage while the 2021 Audi A6 is actually failing — after it restarts you've lost the clue. Don't erase codes until someone who can help has seen them. Post the numbers (or the code) and people can get more specific. If the story changes I'll post the new data.
FlatSixMilesCommunity StarterCommunity StarterJun 13, 2026permalink
Checked the easy stuff on the 2021 Audi A6 and found one clue worth chasing before I book a shop. Might be overthinking it, but I'd rather overthink than overspend.
CommuterSeller940Community StarterCommunity StarterJun 13, 2026permalink
Log the conditions before you spend. Move a coil or plug on the 2021 Audi A6 if it's cylinder-specific and see whether the code follows. That's the branch I'd chase this week. On “buzzing noise only at one engine rpm,” that was the fork that mattered for me. That's the sequence I'd use. If your situation is the opposite, ignore me. Only after sitting overnight so far.
UsedCarMilesCommunity StarterCommunity StarterJun 13, 2026permalink
Ask what changed right before it started. Move a coil or plug on the 2021 Audi A6 if it's cylinder-specific and see whether the code follows. That's the branch I'd chase this week. No need to make it theatrical. Heat soak after errands is the other window.
RoadTraveler73Community StarterCommunity StarterJun 13, 2026permalink
Start with the test that can prove you wrong. Two 2021 Audi A6s can feel identical and have different causes, so measure before you copy someone else's repair. Don't erase codes until someone who can help has seen them. Keep sale price, fees, and rate as three different conversations. I refuse to clear codes until someone else sees them.
RoadTraveler73Community StarterCommunity StarterJun 13, 2026permalink
Fair point. Counterpoint: Move a coil or plug on the 2021 Audi A6 if it's cylinder-specific and see whether the code follows. Don't erase codes until someone who can help has seen them. Write the result down so the next test isn't a repeat of the last one. Your commute and mine probably aren't the same, but the test still applies. That's my plan before I call anyone.
TireBuilder162Community StarterCommunity StarterJun 13, 2026permalink
This is usually cheaper to test than to guess. Loaded-suspension checks on the 2021 Audi A6 catch play that a wheels-hanging inspection misses. Don't erase codes until someone who can help has seen them. I'd want a dollar figure or a measured spec, not 'should be fine.' Video is ugly but it shows the hesitation.
UsedCarMilesCommunity StarterCommunity StarterJun 14, 2026permalink
Yes, with one caveat: Get a real battery/charging test on the 2021 Audi A6, not just resting voltage, before blaming a module. Save the big job until that test fails. That's the sequence I'd use. Heat soak after errands is the other window.
TireBuilder162Community StarterCommunity StarterJun 13, 2026permalink
Start with the test that can prove you wrong. Write temp, speed, and in-gear vs coast when the 2021 Audi A6 does it — then decide on parts. You'll know quickly if you're on the wrong tree. Run the total, not the monthly, before you commit. I've seen both outcomes, which is why I'd test instead of assume. Trying not to diagnose from the couch.
UsedCarMilesCommunity StarterCommunity StarterJun 13, 2026permalink
Intermittent stuff lies if you only catch it once. Capture voltage while the 2021 Audi A6 is actually failing — after it restarts you've lost the clue. That's the branch I'd chase this week. On “buzzing noise only at one engine rpm,” that was the fork that mattered for me. That's the sequence I'd use. Climate here is different, so treat that as a local data point. Trying not to diagnose from the couch.
RoadTraveler73Community StarterCommunity StarterJun 14, 2026permalink
Asking because it changes the advice: Two 2021 Audi A6s can feel identical and have different causes, so measure before you copy someone else's repair. If the cheap test changes it, stop and reassess. Write the result down so the next test isn't a repeat of the last one. No warning lights, which is why I'm documenting it.
TireBuilder162Community StarterCommunity StarterJun 14, 2026permalink
If it were in my driveway, capture voltage while the 2021 Audi A6 is actually failing — after it restarts you've lost the clue. Save the big job until that test fails. I'd want a dollar figure or a measured spec, not 'should be fine.' I'd rather pay for diagnosis than a second guess-repair.
RoadTraveler73Community StarterCommunity StarterJun 14, 2026permalink
Log the conditions before you spend. A pressure test beats staring at a dry driveway if the 2021 Audi A6 is losing coolant with no puddle. Save the big job until that test fails. On “buzzing noise only at one engine rpm,” that was the fork that mattered for me. Keep sale price, fees, and rate as three different conversations. Not interested in a five-hour wait for a shrug.
RoadScout307Community StarterCommunity StarterJun 14, 2026permalink
If it were in my driveway, get a real battery/charging test on the 2021 Audi A6, not just resting voltage, before blaming a module. That's the branch I'd chase this week. This is from a 2021 Audi A6 in Chicago with 91,000 miles. If it doesn't change the out-the-door or the repair estimate, it's noise. I'd sleep better after that step, even if it finds nothing. Happens in gear, not in park, for what that's worth.
SunBeltDadCommunity StarterCommunity StarterJun 14, 2026permalink
I'd push back a little: Loaded-suspension checks on the 2021 Audi A6 catch play that a wheels-hanging inspection misses. You'll know quickly if you're on the wrong tree. Any freeze-frame data saved? Make the next action something you can finish this week. I'm in no rush to be a hero on it.
SunBeltDadCommunity StarterCommunity StarterJun 14, 2026permalink
If it were in my driveway, get a real battery/charging test on the 2021 Audi A6, not just resting voltage, before blaming a module. That's the branch I'd chase this week. Any freeze-frame data saved? I'd sleep better after that step, even if it finds nothing. No warning lights, which is why I'm documenting it.
WeekendDriver470Community StarterCommunity StarterJun 14, 2026permalink
Quick add on that: A pressure test beats staring at a dry driveway if the 2021 Audi A6 is losing coolant with no puddle. Save the big job until that test fails. That's the sequence I'd use. I'd rather be boring and correct. Heat soak after errands is the other window.
RoadTripDIYerCommunity StarterCommunity StarterJun 14, 2026permalink
Log the conditions before you spend. Capture voltage while the 2021 Audi A6 is actually failing — after it restarts you've lost the clue. If the cheap test changes it, stop and reassess. On “buzzing noise only at one engine rpm,” that was the fork that mattered for me. Do that first. Parking it somewhere I can hear it better next time.
FlatSixMilesCommunity StarterCommunity StarterJun 14, 2026permalink
It did buzzing noise only at one engine rpm twice this week, both times after sitting. No change in mileage feel. If that fails I'll eat the diagnostic fee.
SunBeltDadCommunity StarterCommunity StarterJun 14, 2026permalink
Start with the test that can prove you wrong. Swap the cheap/easy piece first on the 2021 Audi A6 and see if the fault moves. Save the big job until that test fails. Have you gotten a second quote in writing? Not interested in a five-hour wait for a shrug.
DealHauler287Community StarterCommunity StarterJun 15, 2026permalink
Fair point. Counterpoint: If a shop can't duplicate it on the 2021 Audi A6, bring a video plus freeze-frame data, not just a story. You'll know quickly if you're on the wrong tree. If it doesn't change the out-the-door or the repair estimate, it's noise. Happens in gear, not in park, for what that's worth.
WeekendDriver470Community StarterCommunity StarterJun 14, 2026permalink
I'd want a measurement, not a hunch. Get a real battery/charging test on the 2021 Audi A6, not just resting voltage, before blaming a module. You'll know quickly if you're on the wrong tree. That's the sequence I'd use. Not trying to scare you — just skip the expensive first guess. Video is ugly but it shows the hesitation.
NoMarkupFanCommunity StarterCommunity StarterJun 14, 2026permalink
Start with the test that can prove you wrong. A pressure test beats staring at a dry driveway if the 2021 Audi A6 is losing coolant with no puddle. If the cheap test changes it, stop and reassess. This is from a 2021 Audi A6 in Chicago with 91,000 miles. I'd want that in writing, not as a promise. Your commute and mine probably aren't the same, but the test still applies. If that fails I'll eat the diagnostic fee.
FlatSixSeller408Community StarterCommunity StarterJun 14, 2026permalink
Quick add on that: Write temp, speed, and in-gear vs coast when the 2021 Audi A6 does it — then decide on parts. If the cheap test changes it, stop and reassess. Take it or leave it — that's what I'd do. Doing the boring step first on purpose.
FlatSixMilesCommunity StarterCommunity StarterJun 14, 2026permalink
It did buzzing noise only at one engine rpm twice this week, both times after sitting. No change in mileage feel. This is the version I'd tell a friend.
PistonCamperCommunity StarterCommunity StarterJun 14, 2026permalink
I'd push back a little: Two 2021 Audi A6s can feel identical and have different causes, so measure before you copy someone else's repair. That's the branch I'd chase this week. If you share a photo of the worksheet, easier to sanity-check. I've seen both outcomes, which is why I'd test instead of assume. Might be overthinking it, but I'd rather overthink than overspend.
FlatSixMilesCommunity StarterCommunity StarterJun 14, 2026permalink
I went back under the 2021 Audi A6 and it only happens after a heat soak, not on a cold start. I'll update if anything new shows up.
UsedCarMilesCommunity StarterCommunity StarterJun 14, 2026permalink
Intermittent stuff lies if you only catch it once. A pressure test beats staring at a dry driveway if the 2021 Audi A6 is losing coolant with no puddle. Save the big job until that test fails. On “buzzing noise only at one engine rpm,” that was the fork that mattered for me. That's the sequence I'd use. If your situation is the opposite, ignore me. Next check is the cheap one I can do in a driveway.
UsedCarMom938Community StarterCommunity StarterJun 14, 2026permalink
Log the conditions before you spend. Get a real battery/charging test on the 2021 Audi A6, not just resting voltage, before blaming a module. That's the branch I'd chase this week. On “buzzing noise only at one engine rpm,” that was the fork that mattered for me. Keep sale price, fees, and rate as three different conversations. I'll update if anything new shows up.
RoadTraveler73Community StarterCommunity StarterJun 14, 2026permalink
I wouldn't throw parts yet. Move a coil or plug on the 2021 Audi A6 if it's cylinder-specific and see whether the code follows. If the cheap test changes it, stop and reassess. Keep sale price, fees, and rate as three different conversations. Only after sitting overnight so far.
RoadTraveler73Community StarterCommunity StarterJun 14, 2026permalink
I'd want a measurement, not a hunch. Move a coil or plug on the 2021 Audi A6 if it's cylinder-specific and see whether the code follows. Save the big job until that test fails. Time, temperature, and whether it's in gear are the notes that actually help a shop. Next check is the cheap one I can do in a driveway.
UsedCarMom938Community StarterCommunity StarterJun 14, 2026permalink
I'd want a measurement, not a hunch. Loaded-suspension checks on the 2021 Audi A6 catch play that a wheels-hanging inspection misses. Don't erase codes until someone who can help has seen them. Write the result down so the next test isn't a repeat of the last one. Checking again after work.
NoMarkupFanCommunity StarterCommunity StarterJun 15, 2026permalink
That's a good start, but I wouldn't stop there. Write temp, speed, and in-gear vs coast when the 2021 Audi A6 does it — then decide on parts. Save the big job until that test fails. Verbal 'we'll take care of it' is not a plan. I'll poke at it this weekend.
CommuterSeller940Community StarterCommunity StarterJun 16, 2026permalink
Not convinced that's the whole story. Loaded-suspension checks on the 2021 Audi A6 catch play that a wheels-hanging inspection misses. Save the big job until that test fails. This is from a 2021 Audi A6 in Chicago with 91,000 miles. No need to make it theatrical. Worth doing even if the car feels fine right now. I'll poke at it this weekend.
RoadTraveler73Community StarterCommunity StarterJun 14, 2026permalink
Intermittent stuff lies if you only catch it once. Write temp, speed, and in-gear vs coast when the 2021 Audi A6 does it — then decide on parts. You'll know quickly if you're on the wrong tree. On “buzzing noise only at one engine rpm,” that was the fork that mattered for me. Keep sale price, fees, and rate as three different conversations. Climate here is different, so treat that as a local data point. Not driving it hard until I know more.
FlatSixMilesCommunity StarterCommunity StarterJun 14, 2026permalink
OP here — recorded a short video and noted speed, temp, and whether it was in gear. Doing the boring step first on purpose.
RoadTripDIYerCommunity StarterCommunity StarterJun 15, 2026permalink
Quick add on that: A pressure test beats staring at a dry driveway if the 2021 Audi A6 is losing coolant with no puddle. You'll know quickly if you're on the wrong tree. On “buzzing noise only at one engine rpm,” that was the fork that mattered for me. This is from a 2021 Audi A6 in Chicago with 91,000 miles. Stop there until you know. Might be overthinking it, but I'd rather overthink than overspend.
NoMarkupFanCommunity StarterCommunity StarterJun 16, 2026permalink
Yes, with one caveat: Loaded-suspension checks on the 2021 Audi A6 catch play that a wheels-hanging inspection misses. That's the branch I'd chase this week. On “buzzing noise only at one engine rpm,” that was the fork that mattered for me. This is from a 2021 Audi A6 in Chicago with 91,000 miles. Verbal 'we'll take care of it' is not a plan. Climate here is different, so treat that as a local data point. Not interested in a five-hour wait for a shrug.
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