Diagnostic article Generic OBD-II
P2055: second DEF valve control has a short-to-supply signature
P2055 detects a hardware short-to-battery condition on DEF metering valve 2 low-side control.
Read before applying this article
Documented application
Documented 2025 GM diagnostic parameter monitor in 25OBDG04B.pdf; model, engine and calibration applicability require vehicle-specific confirmation.
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 reviewed GM P2055 monitor concerns DEF metering valve 2, described in the dictionary as bank 1 unit 2. Its circuit-high label refers to a low-side control path shorted to battery. It does not mean that reductant pressure or commanded dosing quantity is too high.
The hardware result is the evidence
The controller uses the second-valve power-short fault status. The related enable status must be different from indeterminate before the diagnostic is valid. An uninitialized or unavailable result therefore cannot be treated as an electrical pass.
No external voltage cutoff is printed on this page. The description supports the fault direction and channel assignment but does not provide enough information to identify a particular wire or condemn the metering valve. That distinction is especially useful when several reductant-system codes are present together.
Qualification and follow-up
The test must be enabled by calibration, battery voltage must exceed 11 volts, and the system must be key-on or engine-running outside cranking. It needs 30 failing samples out of 60 on a 100-millisecond time basis. GM lists Type A, one-trip reporting.
Confirmation should focus on a completed valve 2 power-short check with a valid hardware result. A restored pressure reading elsewhere in the system does not independently prove that this control path has recovered. The source establishes no repair part, circuit location or broad model coverage. Use the exact vehicle's service information to identify the installed second dosing channel and its diagnostic procedure.
Source: GM monitor, PDF page 779.
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
Reductant Injection Valve Circuit High Bank 1 Unit 2
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