120308 has a source-scoped interpretation in a manufacturer document. Check the raw form, vehicle conditions and original bulletin before using it.
This meaning belongs to the cited manufacturer document and its conditions. It is not a universal code definition, a VIN-specific match, a driving clearance or a parts diagnosis. Independent safety review remains pending.
This BMW document supports only its stated code and vehicle context. The code alone cannot identify a failed part, prove that another make uses the same definition, or clear a car for driving. Compare your full scan with the current exact-vehicle service information.
Read the BMW original: N55 low boost 2C57/120308 diagnostic guidance Source date: 2013-03; research checked: 2026-11-01.
What the manufacturer document says
The same root can have a different meaning or role in another module or vehicle. Preserve the full raw code and suffix rather than applying this table to every car.
| Raw form | Meaning in source | Document | Case context |
|---|---|---|---|
| 120308 | Charge-pressure control plausibility: boost pressure too low in this BMW DME context. | BMW SI B12 16 11 | BMW N55 2C57/120308: air path and vacuum diagnosis first |
| 120308 | Low-boost plausibility indication in the F-series group. | BMW SI B12 36 15 | BMW Valvetronic and boost faults: mechanical versus software |
Vehicle scope recorded in the source
- BMW N55 chassis E70/E71/E82/E84/E88/E90/E92/E93/F01/F02/F07/F10/F12/F13/F25/F30 · year not established · N55; Chassis/engine scope only; model-year table not supplied
- BMW N20/N26/N55 applications · year not established · N20 / N26 / N55; Produced through November 2015; confirm actual chassis and US-market model
What to record before clearing the code
- Disclose intake/tuning changes and save the original BMW code format.
- Record the exact OEM codes and whether the complaint is intermittent.
- Note other codes and the exact dashboard message; a generic reader may miss the affected module.
Questions before a repair or part order
- Do not prepend P to a BMW OEM code, isolate vacuum lines yourself or substitute boost tuning for diagnosis.
- Do not buy a Valvetronic motor from the message alone or attempt unauthorized flashing.
- Does the current manufacturer document cover this VIN, engine, build date and symptom?
- Is a recall, warranty or newer service communication relevant? A bulletin alone is not free-repair eligibility.
How to use this research note
The source document is historical and may have a later revision. Its cited vehicle table is a condition to verify, not a complete list of affected VINs. A code can be secondary to another fault. If braking, steering, propulsion, temperature, smoke, fuel or high-voltage behavior is unsafe, stop safely and seek qualified help rather than using this page to continue driving.
Sources and scope
- BMW — N55 low boost 2C57/120308 diagnostic guidance (SI B12 16 11) Document: 2013-03 · Research checked: 2026-11-01
- BMW — N20/N26/N55 Valvetronic, air-mass and boost faults (SI B12 36 15) Document: 2015-11 · Research checked: 2026-11-01
Research snapshot: 2026-11-01. Source documents may have newer revisions. Verify current instructions and VIN eligibility with the manufacturer.