EngineDiscussionCommunity Starter

2021 BMW X5 — fuel trims are positive at idle and improve with RPM

RustBeltGuy896Community StarterApr 8, 20262021 BMW X5 xDrive40iColumbus
2021 BMW X5 xDrive40i, about 63,000 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?
permalink

Related listings

6 replies

CamberScout887Community StarterCommunity StarterApr 9, 2026permalink
This is usually cheaper to test than to guess. Capture voltage while the 2021 BMW X5 is actually failing — after it restarts you've lost the clue. Don't erase codes until someone who can help has seen them. Was this after sitting overnight? If that fails I'll eat the diagnostic fee.
CamberScout887Community StarterCommunity StarterApr 9, 2026permalink
Start with the test that can prove you wrong. Get a real battery/charging test on the 2021 BMW X5, not just resting voltage, before blaming a module. That's the branch I'd chase this week. Have you gotten a second quote in writing? I've seen both outcomes, which is why I'd test instead of assume. If this is nothing, great. I want that in data.
TrailGeek611Community StarterCommunity StarterApr 9, 2026permalink
I wouldn't throw parts yet. Two 2021 BMW X5s can feel identical and have different causes, so measure before you copy someone else's repair. You'll know quickly if you're on the wrong tree. I'd want a dollar figure or a measured spec, not 'should be fine.' I keep a notes app thread for this now.
WeekendRoadie414Community StarterCommunity StarterApr 9, 2026permalink
I'd want a measurement, not a hunch. Capture voltage while the 2021 BMW X5 is actually failing — after it restarts you've lost the clue. Don't erase codes until someone who can help has seen them. This is from a 2021 BMW X5 in Columbus with 63,000 miles. If they can't show the line item, I assume it's hiding. Not trying to scare you — just skip the expensive first guess. Not interested in a five-hour wait for a shrug.
QuietHauler799Community StarterCommunity StarterApr 10, 2026permalink
I hear you, though I'd still want a second check. Swap the cheap/easy piece first on the 2021 BMW X5 and see if the fault moves. That's the branch I'd chase this week. On “fuel trims are positive at idle and,” that was the fork that mattered for me. This is from a 2021 BMW X5 in Columbus with 63,000 miles. A shop burned me once by skipping that step. Wrote this up on my lunch break.
RustBeltGuy896Community StarterCommunity StarterApr 9, 2026permalink
I went back under the 2021 BMW X5 and it only happens after a heat soak, not on a cold start. If it repeats twice more I'll book time.
Sign in to reply

Similar discussions