Diagnostic article Generic OBD-II
P0312: cylinder 12 misfire needs a cause beyond the cylinder number
Ross-Tech's P0312 entry covers cylinder 12 misfire and includes mechanical, fuel and ignition causes rather than a single prescribed part.
Read before applying this article
Documented application
Ross-Tech independent VAG diagnostic guidance; match complete fault description and controller. Vehicle-specific notes do not establish universal applicability.
The code alone does not identify a failed part or establish that a vehicle is safe to drive. Confirm the vehicle, reporting module and applicable service procedure.
P0312 reports a misfire on cylinder 12. Ross-Tech includes missing ignition, incorrect fuel metering and compression problems in the checks for this fault. Those are different mechanisms with different repairs; the cylinder number does not tell the technician which mechanism is present.
Mechanical evidence remains relevant
The source explicitly includes compression and base-engine problems. As diagnostic interpretation, that means persistent cylinder-12 misfire after an ignition inspection still needs explanation rather than repeated replacement of ignition parts. The article does not specify a compression value because the reference provides no engine-specific limit.
Fuel pressure, injectors, insufficient fuel and an EVAP purge issue also appear in the source. A fault detected at one cylinder can therefore coexist with a problem affecting the engine more broadly. Review the complete combustion-fault pattern before assuming the cause belongs exclusively to one cylinder's hardware.
What would support a repair
First establish the engine's cylinder numbering from its repair information. Then document a result that meaningfully separates ignition, fuel delivery and compression for the complaint. This is an interpretation of the diagnostic branches, not a copied workshop procedure. Ross-Tech is an independent diagnostic-tool publisher; its P0312 page supplies no universal coil layout, injector access method or replacement instruction that applies to every twelve-cylinder engine.
Article source documents
Source checks describe how the text was prepared; they do not certify a diagnosis or confirm compatibility with every vehicle using this code.
Original code reference
Dictionary definition
Cylinder 12 Misfire Detected
This definition retains its original catalog scope. The article above is limited to its explicitly documented application.
Reference scope
Generic OBD-II definition.
A manufacturer label does not establish the model, year, engine or module to which a diagnosis applies. Read the safety and diagnostic limits.
Definition source
- DTC Database: pinned community code definitions
Source checked · MIT