Diagnostic article Generic OBD-II
P029D: cylinder-1 injector leakage inferred from two failures
P029D detects a mechanical open condition of high-pressure injector 1 in the cited table.
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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.
P029D detects a mechanical open condition of high-pressure injector 1 in the cited table. Its evidence combines cylinder-1 misfire activity with an existing minimum rail-pressure-control error.
Neither condition alone is the whole monitor
The documented misfire counter must exceed 100, and the rail-pressure-control minimum error must be set. The test requires engine speed above 1,520 rpm and below 6,000 rpm, relative air charge below 100 percent, and no electrical high-pressure-injector failure. Statistical inhibition must also be inactive.
The table lists a five-second interval and two-trip reporting. These conditions explain why an isolated cylinder-1 misfire code or an isolated low-pressure observation is not equivalent to a completed P029D diagnosis.
Mechanical interpretation with limits
The absence of an electrical injector fault is an enable condition, not proof that every aspect of the injector circuit is perfect. It allows this monitor to interpret the combined combustion and pressure evidence as a mechanical open/leak pattern.
Verification should address both the cylinder-specific misfire behavior and the pressure-control condition in an eligible operating window. A qualified technician should use the applicable high-pressure-fuel procedure to establish the physical cause. The table does not locate an external fuel leak or provide permission to loosen a pressurized connection.
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
Cylinder 1 - Injector Leaking
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