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2021 Toyota Highlander — fuel trims are positive at idle and improve with RPM — Charlotte owner

RoadDetailerCommunity StarterJan 27, 20262021 Toyota Highlander XLECharlotte
2021 Toyota Highlander XLE, about 9,500 miles. Long-term fuel trims are much more positive at idle than at 2,500 RPM. No obvious misfire. Does that pattern still make an intake/vacuum leak the first place to look?
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12 replies

RustBeltBuilder621Community StarterCommunity StarterJan 27, 2026permalink
If it were mine, I would verify the cheap/easy branch on the 2021 Toyota Highlander before committing to a big repair.
UsedCarTuner681Community StarterCommunity StarterJan 28, 2026permalink
Fair, but in Charlotte, I care more about the thing I will notice every day than the spec-sheet extra. That is from a 2021 Toyota Highlander in Charlotte, so take the climate with a grain of salt.
V8Collector191Community StarterCommunity StarterJan 28, 2026permalink
I would start here: write down what you already tested so the next step is not a repeat.
TowWeekend964Community StarterCommunity StarterJan 28, 2026permalink
Fair, but in Charlotte, I care more about the thing I will notice every day than the spec-sheet extra.
SunBeltDaily76Community StarterCommunity StarterJan 28, 2026permalink
Before you spend money, owner data points help more than a generic forum diagnosis on a 2021 Toyota Highlander.
V8Collector191Community StarterCommunity StarterJan 28, 2026permalink
I would start here: write down what you already tested so the next step is not a repeat. That is from a 2021 Toyota Highlander in Charlotte, so take the climate with a grain of salt.
V8Collector191Community StarterCommunity StarterJan 28, 2026permalink
If it were mine, I would verify the cheap/easy branch on the 2021 Toyota Highlander before committing to a big repair. That is from a 2021 Toyota Highlander in Charlotte, so take the climate with a grain of salt.
RoadDetailerCommunity StarterCommunity StarterJan 28, 2026permalink
OP update: I tried the suggestion from earlier and it only happens under that one condition.
WeekendWrench782Community StarterCommunity StarterJan 28, 2026permalink
I would start here: write down what you already tested so the next step is not a repeat. That is from a 2021 Toyota Highlander in Charlotte, so take the climate with a grain of salt. Happy to compare notes if your setup differs.
RoadDetailerCommunity StarterCommunity StarterJan 28, 2026permalink
Useful — I will report back after I verify that on my 2021 Toyota Highlander.
RustBeltBuilder621Community StarterCommunity StarterJan 30, 2026permalink
Small add: owner data points help more than a generic forum diagnosis on a 2021 Toyota Highlander.
V8Collector191Community StarterCommunity StarterJan 29, 2026permalink
Before you spend money, owner data points help more than a generic forum diagnosis on a 2021 Toyota Highlander. That is from a 2021 Toyota Highlander in Charlotte, so take the climate with a grain of salt.
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