Diagnostic article Generic OBD-II
P2855: Clutch-one charge performance includes excess pressure near the hold state
P2855 checks pressure above the clutch-one model and includes a specific hold-pressure branch when the clutch should transmit no torque.
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Documented application
2025 GM 25OBDG07A Part 2 documented monitor only; its application-matrix filename join is unresolved. No model, engine or universal calibration 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.
The cited P2855 monitor identifies clutch-one pressure above the modeled expectation. Besides general positive pressure-error branches, the source includes a check around hold pressure, the control region used while the clutch is not intended to transmit torque.
The hold branch supplies a concrete distinction
The target must be within about 0.051 bar of hold pressure. Measured pressure exceeding the model by about 1.199 bar for at least 300 ms then meets the listed hold-state failure. These values belong to this calibration’s monitor and are not a universal clutch adjustment specification.
General branches use other model-difference thresholds and confirmation times referenced in the source attachments. They should not be replaced with the hold-branch numbers.
Eligibility makes the comparison meaningful
The controller excludes relevant electrical faults, recovery and adaptive overrides. The redundant shutdown valve must be hydraulically on; superfill must be inactive and ended more than 80 ms earlier. Preserve these states with measured and modeled pressure when verifying the event.
A pressure value alone cannot show whether the clutch was in the hold branch or another control state. This code establishes excess pressure relative to expected behavior, not the exact failed valve, sensor or mechanical component.
Document scope and source
2025 GM 25OBDG07A Part 2 documented monitor only; its application-matrix filename join is unresolved. No model, engine or universal calibration applicability is inferred. These figures explain the cited controller logic, not a vehicle-specific repair instruction. Match the vehicle’s service information before applying them.
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
Clutch A Pressure Charge Performance
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