When your 2024 BMW 3 Series displays the P0305 code, the diagnostic significance depends on which engine is installed. The 2024 3 Series offers both four-cylinder and six-cylinder options. P0305 is valid on the inline-six models (340i) but anomalous on the four-cylinder (330i, 330e).
2024 3 Series Engine Options
The 2024 BMW 3 Series offers the 2.0L B48 turbocharged I-4 (255 hp in 330i) and the 3.0L B58 turbocharged I-6 (382 hp in M340i). Only the inline-six has a cylinder 5.
Inline-Six Diagnosis
On the B58 inline-six, cylinder 5 is toward the rear of the engine. BMW's excellent engine design means spark plug issues are common at higher mileages, along with ignition coil failures and carbon buildup on direct-injection engines.
Four-Cylinder Models
If your 3 Series is a 330i or 330e with the 2.0L turbo, P0305 is anomalous—this engine has only cylinders 1-4. Investigate ECM issues and scan tool compatibility.
Diagnostic Approach
Verify your engine. On M340i, diagnose cylinder 5 using BMW diagnostic equipment. On 330i/330e, check for diagnostic errors.