Diagnostic article Generic OBD-II
P0356: ignition-coil circuit code with inconsistent coil lettering
P0356 is cataloged as ignition coil F primary control circuit/open, while the supplied GM row names coil E.
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Documented application
2025 GM 25OBDG07A Part2 diagnostic monitor documentation; the application-matrix filename mismatch is unresolved, so no model or engine applicability is inferred.
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.
P0356 is cataloged as ignition coil F primary control circuit/open, while the supplied GM row names coil E. That discrepancy prevents this page from serving as a reliable coil-location or cylinder-mapping reference.
The electrical strategy is identifiable
The row describes an open-circuit check of a primary low-side driver. Low voltage during the driver’s off state is its evidence, with an open-path classification of at least 200 kilohms between ECU pin and load. Detection is listed as 0.4 second with two-trip reporting.
The check requires synchronized ignition, engine speed above 1,400 rpm, and an ignition-counter increase above nine so that all cylinders have fired. It therefore is not described as a simple key-on continuity check.
Resolve identity before applying the test
The coil-letter conflict must be reconciled with the actual controller’s DTC information and service diagram. Do not select coil E or coil F solely from this inconsistent row. An implausible printed upper battery-voltage bound is also excluded from this explanation.
Verification should confirm the correctly mapped driver’s electrical monitor completes after its firing and synchronization prerequisites. Ignition circuits require the proper testing equipment; the impedance classification is not an instruction to probe an operating ignition system. This draft remains flagged for source review.
Documentation and applicability
These details describe the monitor in GM’s 2025 25OBDG07A Part2 file. Its application-matrix filename does not match the download index, so model and engine applicability remain unresolved. Use the vehicle’s correct service information before applying these calibration details.
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
Ignition Coil F Primary Control Circuit/Open
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