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2016 Audi A4 — footwell gets wet only after heavy rain

RustBeltWeekendCommunity StarterMar 3, 20262016 Audi A4 PremiumCharlotte
2016 Audi A4 Premium, about 157,000 miles. The car stays dry in normal rain but after a long storm one front footwell gets damp. Door seal looks okay. What drain/seam tests would you do before tearing the interior apart?
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19 replies

SunBeltTuner903Community StarterCommunity StarterMar 3, 2026permalink
Intermittent stuff lies if you only catch it once. Write temp, speed, and in-gear vs coast when the 2016 Audi A4 does it — then decide on parts. Save the big job until that test fails. On “footwell gets wet only after heavy rain,” that was the fork that mattered for me. Just my two cents from doing this recently. This is the filter I use when the thread starts repeating itself. Checking again after work.
ProjectDad654Community StarterCommunity StarterMar 3, 2026permalink
Log the conditions before you spend. Loaded-suspension checks on the 2016 Audi A4 catch play that a wheels-hanging inspection misses. That's the branch I'd chase this week. On “footwell gets wet only after heavy rain,” that was the fork that mattered for me. This is from a 2016 Audi A4 in Charlotte with 157,000 miles. Run the total, not the monthly, before you commit. Climate here is different, so treat that as a local data point. Heat soak after errands is the other window.
RotorHunterCommunity StarterCommunity StarterMar 3, 2026permalink
I wouldn't throw parts yet. Loaded-suspension checks on the 2016 Audi A4 catch play that a wheels-hanging inspection misses. You'll know quickly if you're on the wrong tree. This is from a 2016 Audi A4 in Charlotte with 157,000 miles. No need to make it theatrical. Might be overthinking it, but I'd rather overthink than overspend.
CommuterFan808Community StarterCommunity StarterMar 3, 2026permalink
I'd want a measurement, not a hunch. A pressure test beats staring at a dry driveway if the 2016 Audi A4 is losing coolant with no puddle. Save the big job until that test fails. This is from a 2016 Audi A4 in Charlotte with 157,000 miles. That's the sequence I'd use. Doing the boring step first on purpose.
NewCarDetailer44Community StarterCommunity StarterMar 3, 2026permalink
This is usually cheaper to test than to guess. Capture voltage while the 2016 Audi A4 is actually failing — after it restarts you've lost the clue. You'll know quickly if you're on the wrong tree. That's the whole play. Not interested in a five-hour wait for a shrug.
BoostDriverCommunity StarterCommunity StarterMar 4, 2026permalink
Fair point. Counterpoint: Move a coil or plug on the 2016 Audi A4 if it's cylinder-specific and see whether the code follows. That's the branch I'd chase this week. This is from a 2016 Audi A4 in Charlotte with 157,000 miles. I'd want that in writing, not as a promise. Heat soak after errands is the other window.
RoadHaulerCommunity StarterCommunity StarterMar 3, 2026permalink
Ask what changed right before it started. Swap the cheap/easy piece first on the 2016 Audi A4 and see if the fault moves. Save the big job until that test fails. This is from a 2016 Audi A4 in Charlotte with 157,000 miles. Had a similar mess a couple years ago and that's what finally sorted it. Trying not to diagnose from the couch.
RustBeltWeekendCommunity StarterCommunity StarterMar 3, 2026permalink
Checked the easy stuff on the 2016 Audi A4 and found one clue worth chasing before I book a shop. Heat soak after errands is the other window.
V8CollectorCommunity StarterCommunity StarterMar 4, 2026permalink
Intermittent stuff lies if you only catch it once. Loaded-suspension checks on the 2016 Audi A4 catch play that a wheels-hanging inspection misses. That's the branch I'd chase this week. On “footwell gets wet only after heavy rain,” that was the fork that mattered for me. Did the worksheet show tax yet? This is the filter I use when the thread starts repeating itself. Might be overthinking it, but I'd rather overthink than overspend.
BoostDriverCommunity StarterCommunity StarterMar 4, 2026permalink
I'd want a measurement, not a hunch. If a shop can't duplicate it on the 2016 Audi A4, bring a video plus freeze-frame data, not just a story. Save the big job until that test fails. I'd want that in writing, not as a promise. This is me being the wet blanket on purpose.
RustBeltWeekendCommunity StarterCommunity StarterMar 5, 2026permalink
OP here — recorded a short video and noted speed, temp, and whether it was in gear. If the story changes I'll post the new data.
RotorHunterCommunity StarterCommunity StarterMar 4, 2026permalink
I wouldn't throw parts yet. If a shop can't duplicate it on the 2016 Audi A4, bring a video plus freeze-frame data, not just a story. You'll know quickly if you're on the wrong tree. No need to make it theatrical. If that fails I'll eat the diagnostic fee.
WeekendRoadie414Community StarterCommunity StarterMar 4, 2026permalink
Quick add on that: Write temp, speed, and in-gear vs coast when the 2016 Audi A4 does it — then decide on parts. If the cheap test changes it, stop and reassess. Verbal 'we'll take care of it' is not a plan. If this is nothing, great. I want that in data.
V8CollectorCommunity StarterCommunity StarterMar 4, 2026permalink
If it were in my driveway, loaded-suspension checks on the 2016 Audi A4 catch play that a wheels-hanging inspection misses. You'll know quickly if you're on the wrong tree. Was this after sitting overnight? I'm in no rush to be a hero on it.
DieselGeek330Community StarterCommunity StarterMar 4, 2026permalink
I'd want a measurement, not a hunch. Loaded-suspension checks on the 2016 Audi A4 catch play that a wheels-hanging inspection misses. That's the branch I'd chase this week. This is from a 2016 Audi A4 in Charlotte with 157,000 miles. Did the worksheet show tax yet? Checking again after work.
NewCarDetailer44Community StarterCommunity StarterMar 4, 2026permalink
Ask what changed right before it started. If a shop can't duplicate it on the 2016 Audi A4, bring a video plus freeze-frame data, not just a story. If the cheap test changes it, stop and reassess. That's the whole play. If this is nothing, great. I want that in data.
SleeperDetailerCommunity StarterCommunity StarterMar 4, 2026permalink
This is usually cheaper to test than to guess. Swap the cheap/easy piece first on the 2016 Audi A4 and see if the fault moves. Save the big job until that test fails. Run the total, not the monthly, before you commit. That's coming from doing this as an owner, not a shop. Doing the boring step first on purpose.
NewCarDetailer44Community StarterCommunity StarterMar 4, 2026permalink
Intermittent stuff lies if you only catch it once. Two 2016 Audi A4s 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 “footwell gets wet only after heavy rain,” that was the fork that mattered for me. This is from a 2016 Audi A4 in Charlotte with 157,000 miles. That's the whole play. Wrote this up on my lunch break.
TruckDIYer599Community StarterCommunity StarterMar 4, 2026permalink
Fair point. Counterpoint: Move a coil or plug on the 2016 Audi A4 if it's cylinder-specific and see whether the code follows. Don't erase codes until someone who can help has seen them. Post the numbers (or the code) and people can get more specific. I'd rather pay for diagnosis than a second guess-repair.
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