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2023 GMC Sierra 1500 — dealer cannot reproduce an intermittent warning

BrakeDriverCommunity StarterJun 26, 20262023 GMC Sierra 1500 AT4Seattle
2023 GMC Sierra 1500 AT4, about 50,500 miles. I have brought the car in twice for the same intermittent warning and both visits ended with could-not-reproduce. I have video and timestamps. What is the best way to build a useful paper trail? I am in Seattle. I am trying not to assume the first explanation I see online.
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16 replies

PistonCamper189Community StarterCommunity StarterJun 26, 2026permalink
I wouldn't throw parts yet. Capture voltage while the 2023 GMC Sierra 1500 is actually failing — after it restarts you've lost the clue. Don't erase codes until someone who can help has seen them. Take it or leave it — that's what I'd do. Happens in gear, not in park, for what that's worth.
TireGarageCommunity StarterCommunity StarterJun 26, 2026permalink
I'd want a measurement, not a hunch. Move a coil or plug on the 2023 GMC Sierra 1500 if it's cylinder-specific and see whether the code follows. That's the branch I'd chase this week. Had a similar mess a couple years ago and that's what finally sorted it. I'd sleep better after that step, even if it finds nothing. If this is nothing, great. I want that in data.
TireGarageCommunity StarterCommunity StarterJun 26, 2026permalink
Yes, with one caveat: Swap the cheap/easy piece first on the 2023 GMC Sierra 1500 and see if the fault moves. Don't erase codes until someone who can help has seen them. On “dealer cannot reproduce an intermittent warning,” that was the fork that mattered for me. A shop burned me once by skipping that step. If your situation is the opposite, ignore me. This is me being the wet blanket on purpose.
RotorOwner247Community StarterCommunity StarterJun 27, 2026permalink
Fair point. Counterpoint: If a shop can't duplicate it on the 2023 GMC Sierra 1500, bring a video plus freeze-frame data, not just a story. Save the big job until that test fails. Keep sale price, fees, and rate as three different conversations. I'd rather pay for diagnosis than a second guess-repair.
QuietSeller995Community StarterCommunity StarterJun 27, 2026permalink
Agree — and I'd add this: Loaded-suspension checks on the 2023 GMC Sierra 1500 catch play that a wheels-hanging inspection misses. Don't erase codes until someone who can help has seen them. On “dealer cannot reproduce an intermittent warning,” that was the fork that mattered for me. Had a similar mess a couple years ago and that's what finally sorted it. Might be overthinking it, but I'd rather overthink than overspend.
BrakeDriverCommunity StarterCommunity StarterJun 27, 2026permalink
Cleared nothing. I want service to see the alert on the 2023 GMC Sierra 1500 first. Wrote this up on my lunch break.
RotorOwner247Community StarterCommunity StarterJun 26, 2026permalink
Ask what changed right before it started. Capture voltage while the 2023 GMC Sierra 1500 is actually failing — after it restarts you've lost the clue. That's the branch I'd chase this week. This is from a 2023 GMC Sierra 1500 in Seattle with 50,500 miles. Time, temperature, and whether it's in gear are the notes that actually help a shop. Doing the boring step first on purpose.
CityNerd482Community StarterCommunity StarterJun 26, 2026permalink
Intermittent stuff lies if you only catch it once. Move a coil or plug on the 2023 GMC Sierra 1500 if it's cylinder-specific and see whether the code follows. You'll know quickly if you're on the wrong tree. On “dealer cannot reproduce an intermittent warning,” that was the fork that mattered for me. That's the sequence I'd use. Only after sitting overnight so far.
CommuterSeller940Community StarterCommunity StarterJun 28, 2026permalink
That's a good start, but I wouldn't stop there. Swap the cheap/easy piece first on the 2023 GMC Sierra 1500 and see if the fault moves. If the cheap test changes it, stop and reassess. This is from a 2023 GMC Sierra 1500 in Seattle with 50,500 miles. No need to make it theatrical. I already checked the easy fluid levels.
PistonCamper189Community StarterCommunity StarterJun 27, 2026permalink
I wouldn't throw parts yet. Swap the cheap/easy piece first on the 2023 GMC Sierra 1500 and see if the fault moves. Don't erase codes until someone who can help has seen them. Just my two cents from doing this recently. Your commute and mine probably aren't the same, but the test still applies. No warning lights, which is why I'm documenting it.
BrakeDriverCommunity StarterCommunity StarterJun 27, 2026permalink
It did dealer cannot reproduce an intermittent warning twice this week, both times after sitting. No change in mileage feel. I'd rather pay for diagnosis than a second guess-repair.
ShopEnthusiast239Community StarterCommunity StarterJun 27, 2026permalink
Start with the test that can prove you wrong. Loaded-suspension checks on the 2023 GMC Sierra 1500 catch play that a wheels-hanging inspection misses. If the cheap test changes it, stop and reassess. Just my two cents from doing this recently. Parking it somewhere I can hear it better next time.
CommuterSeller940Community StarterCommunity StarterJun 27, 2026permalink
Not convinced that's the whole story. Capture voltage while the 2023 GMC Sierra 1500 is actually failing — after it restarts you've lost the clue. If the cheap test changes it, stop and reassess. No need to make it theatrical. If the story changes I'll post the new data.
ShopHauler710Community StarterCommunity StarterJun 27, 2026permalink
If it were in my driveway, if a shop can't duplicate it on the 2023 GMC Sierra 1500, bring a video plus freeze-frame data, not just a story. You'll know quickly if you're on the wrong tree. That's the sequence I'd use. That's my plan before I call anyone.
ShopHauler710Community StarterCommunity StarterJun 27, 2026permalink
Ask what changed right before it started. Two 2023 GMC Sierra 1500s 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. This is from a 2023 GMC Sierra 1500 in Seattle with 50,500 miles. No need to make it theatrical. If the story changes I'll post the new data.
RustBeltDaily757Community StarterCommunity StarterJun 27, 2026permalink
Log the conditions before you spend. Capture voltage while the 2023 GMC Sierra 1500 is actually failing — after it restarts you've lost the clue. Save the big job until that test fails. On “dealer cannot reproduce an intermittent warning,” that was the fork that mattered for me. If they can't show the line item, I assume it's hiding. If your situation is the opposite, ignore me. Video is ugly but it shows the hesitation.
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