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Intermittent metallic rattle after cold start

PixelHauler42Community StarterSep 4, 20262021 Audi A6 PrestigeLas Vegas
2021 Audi A6 Prestige, about 14,500 miles. For the first few seconds after a cold start I hear a metallic rattle, then it disappears and won't come back once the engine is warm. No warning lights and it drives normally. Has anyone chased somethign like this without just replacing random parts? Trying to diagnose before I book a shop.
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10 replies

PixelHauler42Community StarterCommunity StarterSep 4, 2026permalink
I went back under the 2021 Audi A6 and it only happens after a heat soak, not on a cold start. Not driving it hard until I know more.
PixelHauler42Community StarterCommunity StarterSep 4, 2026permalink
Tried a second charger / second scan and the story on the 2021 Audi A6 didn't change. Not interested in a five-hour wait for a shrug.
CleanHunterCommunity StarterCommunity StarterSep 4, 2026permalink
I wouldn't throw parts yet. 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. Verbal 'we'll take care of it' is not a plan. This is me being the wet blanket on purpose.
EuroNomad49Community StarterCommunity StarterSep 4, 2026permalink
If it were in my driveway, two 2021 Audi A6s can feel identical and have different causes, so measure before you copy someone else's repair. Save the big job until that test fails. Time, temperature, and whether it's in gear are the notes that actually help a shop. Parking it somewhere I can hear it better next time.
EuroNomad49Community StarterCommunity StarterSep 4, 2026permalink
Ask what changed right before it started. 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. Time, temperature, and whether it's in gear are the notes that actually help a shop. A day of patience here is cheaper than a wrong part. Not interested in a five-hour wait for a shrug.
EuroNomad49Community StarterCommunity StarterSep 4, 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. Don't erase codes until someone who can help has seen them. On “intermittent metallic rattle after cold start,” that was the fork that mattered for me. Keep sale price, fees, and rate as three different conversations. I'd rather look cautious in this thread than stuck later.
CleanGuy8Community StarterCommunity StarterSep 4, 2026permalink
Yes, with one caveat: 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. On “intermittent metallic rattle after cold start,” that was the fork that mattered for me. I'd want that in writing, not as a promise. This is the filter I use when the thread starts repeating itself. I'll poke at it this weekend.
EuroNomad49Community StarterCommunity StarterSep 4, 2026permalink
Asking because it changes the advice: 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. Time, temperature, and whether it's in gear are the notes that actually help a shop. I'd rather pay for diagnosis than a second guess-repair.
CleanGuy8Community StarterCommunity StarterSep 4, 2026permalink
Start with the test that can prove you wrong. 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. This is from a 2021 Audi A6 in Las Vegas with 14,500 miles. Verbal 'we'll take care of it' is not a plan. Might be overthinking it, but I'd rather overthink than overspend.
BoostedRoadie3Community StarterCommunity StarterSep 4, 2026permalink
I'd want a measurement, not a hunch. If a shop can't duplicate it on the 2021 Audi A6, bring a video plus freeze-frame data, not just a story. If the cheap test changes it, stop and reassess. This is from a 2021 Audi A6 in Las Vegas with 14,500 miles. If they can't show the line item, I assume it's hiding. Wrote this up on my lunch break.
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