Diagnostic article Generic OBD-II
P2820: a documented park-lock valve stuck-off monitor
P2820 can identify a hydraulic park-lock engagement valve fault in the documented GM transmission calibration.
Read before applying this article
Documented application
Documented 2025 GM gm-2025-07a-2 monitor only; vehicle, engine and controller applicability must be established separately. The download-index/application-matrix filename join is unresolved; no model or engine 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.
Although a generic dictionary calls P2820 “pressure control solenoid J performance/stuck off,” this particular GM table assigns it to the park-lock engagement valve. That distinction is essential: this article explains the park-lock calibration in 25OBDG07A Part 2, not every transmission using the code.
What fails the monitor
The controller observes an attempted drive-away while the park-lock position remains locked and little output movement occurs. Its listed conditions include vehicle speed at or below 10 km/h, output speed at or below 100 rpm, clutch torque above 75 Nm and the brake not pressed. Oil temperature must be at least 40°C. The decision also uses repeated failed current-profile checks for the engagement valve, with a confirmation count of at least three and a drive-away failure period of at least 3,000 milliseconds.
A locked park mechanism alone cannot distinguish the engagement valve from the latching valve. The table specifically uses the engagement valve's current profile to make that distinction. The latching valve must be logically hydraulic-on, and relevant electrical faults must be absent.
What the evidence means
Review commanded park-lock state, reported position and the current-profile result together. A position that remains locked without the current-profile failures does not reproduce the complete documented diagnosis. Equally, electrical or position-sensor faults can prevent the hydraulic inference from being valid. These are professional transmission tests involving vehicle restraint; the table is not an instruction to force the vehicle against the parking lock. Verification must establish normal park-lock release and completion of the applicable diagnostic routine.
Source and applicability
Documented 2025 GM gm-2025-07a-2 monitor only; vehicle, engine and controller applicability must be established separately. The download-index/application-matrix filename join is unresolved; no model or engine is inferred. GM monitor table, PDF page 998.
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
Pressure Control Solenoid J Performance/Stuck Off
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