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2020 GMC Yukon — single-cylinder misfire comes and goes

RoadTripScout979Community StarterApr 20, 20262020 GMC Yukon DenaliTampa
2020 GMC Yukon Denali, about 46,000 miles. A cylinder-specific misfire code appeared after one rough start, then cleared and the engine feels normal. Plugs are not very old. Would you swap coils, inspect plugs, look at injector data, or wait for it to return? I am in Tampa.
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6 replies

TowGarage486Community StarterCommunity StarterApr 21, 2026permalink
Start with the test that can prove you wrong. Move a coil or plug on the 2020 GMC Yukon if it's cylinder-specific and see whether the code follows. You'll know quickly if you're on the wrong tree. No need to make it theatrical. Happens in gear, not in park, for what that's worth.
OldSchoolMechanicish284Community StarterCommunity StarterApr 21, 2026permalink
Ask what changed right before it started. A pressure test beats staring at a dry driveway if the 2020 GMC Yukon is losing coolant with no puddle. Don't erase codes until someone who can help has seen them. Not gospel, but it saved me a headache. Doing the boring step first on purpose.
CanyonOwner864Community StarterCommunity StarterApr 21, 2026permalink
Ask what changed right before it started. If a shop can't duplicate it on the 2020 GMC Yukon, 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. Cold start is when I can actually reproduce it.
DailyHauler884Community StarterCommunity StarterApr 22, 2026permalink
I hear you, though I'd still want a second check. Two 2020 GMC Yukons 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. On “single-cylinder misfire comes and goes,” that was the fork that mattered for me. If it doesn't change the out-the-door or the repair estimate, it's noise. Heat soak after errands is the other window.
TowGarage486Community StarterCommunity StarterApr 22, 2026permalink
Same neighborhood, different next step: Move a coil or plug on the 2020 GMC Yukon if it's cylinder-specific and see whether the code follows. You'll know quickly if you're on the wrong tree. That's the sequence I'd use. If that fails I'll eat the diagnostic fee.
ShiftHunter834Community StarterCommunity StarterApr 22, 2026permalink
I wouldn't throw parts yet. Write temp, speed, and in-gear vs coast when the 2020 GMC Yukon does it — then decide on parts. You'll know quickly if you're on the wrong tree. This is from a 2020 GMC Yukon in Tampa with 46,000 miles. I'd want a dollar figure or a measured spec, not 'should be fine.' Worth doing even if the car feels fine right now. Wrote this up on my lunch break.
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