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2018 340i Rough Idle & Reduced Power - VANOS Issue?

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Kim L. · rep 0 · May 22, 4:04 AM · 1 replies · solved · Question

Hey everyone, I've got a 2018 BMW 340i (F30) with the B58 engine that's been acting up lately. When I start it cold, the idle is really rough for about 30 seconds, and sometimes it feels like it's lacking power, especially at lower RPMs.

The check engine light came on a couple of times, but then went off. I managed to pull some codes with a generic OBD scanner before it cleared, and I saw P0012 and P0015, which point to camshaft position timing over-retarded.

Could this be a VANOS solenoid issue, or something more serious like the timing chain? The car only has about 60k miles on it. Any advice on what to check first or common fixes for this model year?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 4:04 AM

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ClearTheCode guidance (Bmw · Engine & drivetrain)

Summary: For 2018 340i Rough Idle & Reduced Power - VANOS Issue?, work through these steps on your 2016+ vehicle:

  1. Confirm the symptom — note when it happens (cold start, highway, after fuel fill, etc.).
  2. Scan codes — save all pending/stored DTCs; don't clear until you've recorded them.
  3. Check TSBs & recalls — look up your VIN for open campaigns and known fixes.
  4. Inspect the obvious — related fuses, connectors, fluid level, and recent repairs.
  5. Test the common fix — follow model-specific service procedures; one change at a time.
  6. Escalate if needed — burning smell, no brakes, overheating, or stalling in traffic → shop visit.

Owner reported: Hey everyone, I've got a 2018 BMW 340i (F30) with the B58 engine that's been acting up lately. When I start it cold, the idle is really rough for about 30 seconds, and sometimes it feels like it's lacking power, especially at lower RPMs.

The check engine light came on a couple of times, but then went off. I managed to pull some codes with a generic OBD scanner before it cleared, and I saw P0012 a…

This is educational guidance, not a substitute for hands-on diagnosis.

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